Thursday, April 24, 2025
Why did this complaint occur? Using the Fishbone Diagram and 5 Whys to strengthen complaint handling
Intro
If the same issues keep resurfacing, there’s a deeper cause that’s being overlooked. And more often than not, it’s not what you think. It’s easy to assume you need more staff, but if good people keep leaving, the issue probably isn’t the role; it’s the process breaking down.
Fixing complaints sustainably means finding and addressing the real causes, not just the visible symptoms.
And to do that, you need time out of the trench and with the right tools.
Here’s one combination that helped me more than once shift from chaotic working to one of clarity:
The Fishbone Diagram and the Five Whys analysis.
Why did this complaint occur? (Using the 5 Whys method to find the underlying systemic cause)
Most complaints have an obvious trigger. But the trigger is rarely the real cause.
The 5 Whys method helps you move past surface issues and identify the underlying systemic cause that keeps generating repeat complaints.
In practice, this matters because complaint teams do not struggle with one-off errors. They struggle with repeat patterns: the same delays, the same handoffs, the same inconsistent decision making, and the same avoidable escalation risk.
You will often hear people jump straight to the 5 Whys. But in complaint handling, the best results usually come from doing one step first: mapping the possible drivers using a Fishbone Diagram. Then you apply the 5 Whys to the most likely causes.
Step 1:Use a Fishbone Diagram to map what is driving the complaint
What is the purpose of a Fishbone Diagram?
Also known as the Ishikawa Diagram, the fishbone is a visual cause-and-effect problem-solving tool. It helps teams identify root causes by organising contributing factors into structured categories.
It’s a great way to:
Cut through the noise to find the real problem
Encourages critical thinking
Brings different perspectives together
Helps teams ask better questions
What does a Fishbone Diagram help you identify?
During the Analyse phase of improvement work (e.g. DMAIC: Define, Measure, Analyse, Improve, Control), a fishbone diagram helps you:
Break down complex issues into manageable parts
Explore contributing factors
Moves you beyond assumptions to find root causes and supporting data
I've handed the fishbone template to the complaint teams and asked them to complete it, usually over a 48 to 72-hour period, and while handling live cases. There’s nothing like working on a real-life problem to trigger the mind!
Quick definitions (so you can use this in your next team session)
Things to focus on:
Symptom: what you see (late responses, repeat contacts)
Trigger: what happened (missed call, unclear letter, delay)
Root cause: why it keeps happening (process design, approvals bottleneck, unclear ownership)
Corrective action: what you change now
Preventive action: what stops repeat complaints
When to use a Fishbone Diagram in complaint handling
Use it when:
The same issue keeps resurfacing (e.g. missed SLAs)
Resolution happens, but complaints aren’t closed out (e.g. FOS escalations)
There’s disagreement in the team about what’s going wrong
You need to show others what’s behind recurring issues
You need to investigate complaint trends rather than individual cases
Example: Poor service levels
Let’s say service levels are dropping. You can use a fishbone to map potential causes under these six complaint-handling categories:
People: high turnover, low morale, inconsistent decisions
Processes & policies: no escalation path, unclear ownership
Technology: manual logging, siloed tools
Customer expectations: slow updates, lack of empathy
Regulatory compliance: missing audit trails, poor documentation
Measurement & feedback: no trend tracking, weak data loops from different sources
Once you’ve built your fishbone diagram, you can apply the Five Whys.
Step 2: Use the 5 Whys root cause analysis
What are the Five Whys of root cause analysis?
The 5 Whys is a simple questioning technique that helps you dig deeper by repeatedly asking: Why?
You ask why for each symptom until you reach the root cause. The idea is to break down the problem in five steps or fewer.
I have used this approach with regulated complaint teams when service levels dropped, FOS escalations increased, or complaints kept bouncing between case handlers with no clear ownership.
How the Fishbone Diagram and Five Whys work together
Let’s look at an example:
Problem: Poor service levels
Why are service levels poor? → Complaints take too long to resolve
Why? → Cases are stuck waiting for approvals
Why? → Too many cases for the team leaders to review
Why? → No clear escalation process
Why? → No prioritisation policy in place
Root cause: Lack of structured escalation and prioritisation.
💡Tip: Split the team into two or three sub-teams and issue each with a problem, a fishbone diagram, and let it sit with them for a day or two. Then ask them to each apply the Five Whys to their fishbones and compare findings.
Fishbone Diagram categories for complaint handling
What are the 6 elements of a Fishbone Diagram for complaints?
Adapted for regulated complaints handling, we recommend these six categories:
People
Process & policy
Technology
Customer expectations
Regulatory compliance
Measurement & feedback
What are the 7 traditional categories?
The original Ishikawa model uses:
People
Processes
Physical evidence
Placement
Product
Promotion
Price
You don’t need to use all seven. Swap categories to match the complaint type, product, or operating model.
This tool is widely adopted across regulated sectors, including healthcare, financial services, and customer service, for example, the NHS also recommends Fishbone diagrams as part of root cause analysis.
5 steps for creating a Fishbone Diagram
Write the problem statement clearly at the 'head' of the fish
Draw the main 'bones' (categories) off from the spine
Brainstorm causes within each category
Ask 'why?' repeatedly to go deeper
Highlight potential root causes for validation and action
Why use the Fishbone with the 5 Whys?
The Fishbone helps you look wide. The 5 Whys helps you look deep.
Together:
You map causes clearly and concisely
Then dig into what's really driving the problem
Without relying on guesses and assumptions*
Advantages of the Fishbone Diagram
Easy to understand and explain
Useful when time is limited, or resources are scarce
Helps simplify complex issues
Great for team collaboration and root cause sessions
Sparks ideas even when you’re not sure where to start
Provides a visual map you can return to
Visuals help stakeholders remember your message
Disavantages of the Fishbone Diagram
Can get too broad or messy if not focused on the problem
* May rely too heavily on opinions if not supported by data
Doesn’t prioritise causes; it just maps them
Can lead to false leads if the categories aren’t well chosen
💡 Tip: Always bring in the complaint data and team insight to balance out the diagram.
How to create a Fishbone Diagram in Word
Open a blank document
Use Insert > Shapes to draw a horizontal arrow
Add text boxes branching off the spine
Label with your chosen categories
Add contributing causes under each
Why root cause analysis matters in FCA-regulated complaint handling
Root cause analysis is not just a process improvement exercise. In FCA-regulated complaint handling, it supports stronger oversight and decision confidence.
It helps because:
Repeat complaints can point to systemic issues rather than isolated errors
Leadership can evidence what changed and why
Teams shift from reactive handling to prevention and control
Better complaint MI reduces avoidable escalation risk and supports outcomes-led thinking aligned to Consumer Duty
Complaint management toolbox
Fixing complaints starts with understanding what’s broken, not just what’s visible.
This is one small tool that can help you get there faster. And if you are building stronger complaint handling foundations, you may also find our blog, The 5 Cs of complaint handling and how to use the framework effectively, useful.
FAQs about the Fishbone Diagram and 5 Whys
What is the difference between a root cause and a trigger in complaint handling?
A trigger is the event that led to the complaint (for example a missed call back). The root cause is why that trigger happened and keeps happening (for example unclear ownership or a broken approval process).
What should I record as the root cause in a complaint system?
Record all of the systemic causes that can be fixed and monitored, such as unclear process steps, missing controls, poor handoffs, lack of prioritisation rules, or inconsistent decision-making guidance.
Is the Fishbone Diagram better than 5 Whys?
They do different jobs. The Fishbone Diagram helps you map causes across categories. The 5 Whys helps you dig deeper into the most likely causes. Used together, they reduce guesswork and improve confidence.
How do you stop Fishbone sessions turning into opinions?
Bring complaint MI, real examples, and evidence. Encourage teams to test assumptions, not just list them. The tool should surface causes to validate, not conclusions to agree on.
How can I run this exercise without pulling the team off live cases?
Use a 48 to 72 hour approach: give the template to small groups and let them contribute alongside casework, then run short review sessions to agree root causes and next actions.