Why this answer
What actually matters
- The protection depends on why accurate bills were not produced.
- Customer obstruction or unreasonable failure to provide information can matter.
- Separate protected historic charges from recent undisputed usage.
- Ask the supplier to identify the periods and readings involved.
Important nuance
When the statement may have a point
- Older debt shown on bills issued correctly at the time is different from a new back-bill.
- The protection may not apply where the customer behaved obstructively.
What you could say
Keep the response tied to the actual rule.
Evidence
What to have beside you
- Bills and statements covering the disputed period
- Meter readings, photographs and meter serial numbers
- Tenancy or completion records showing responsibility dates
- Complaint correspondence and any deadlock letter
If they still refuse
Move the dispute forward.
- Ask the supplier to explain its calculation, readings and legal or licence basis in writing.
- Keep paying undisputed ongoing usage where possible while identifying the disputed amount separately.
- After deadlock or the applicable waiting period, consider the Energy Ombudsman for an eligible dispute.
Read the full rules
Go deeper before escalating.
Official sources