Car Insurance Claim Refused

The FCA's rules say an insurer must handle claims promptly and fairly, give you reasonable guidance to help you make a claim and appropriate updates on progress, not unreasonably reject a claim, and settle claims promptly once settlement terms are agreed (ICOBS 8.1.1R). source

For consumer policies, an insurer rejecting a claim because of a misrepresentation is generally unreasonable unless it was a 'qualifying misrepresentation': you failed to take reasonable care not to misrepresent, and the insurer can show it would not have written the policy at all, or only on different terms, without it. source

Rejecting a claim because you breached a condition or warranty is generally unreasonable unless the circumstances of the claim are connected to the breach (for contracts on or after 1 August 2017, with exceptions in sections 10 and 11 of the Insurance Act 2015). source

The Financial Ombudsman handles motor insurance complaints including vehicle theft, repairs, valuations and write-offs, fault claims and no-claims bonuses, GAP, telematics and breakdown cover. It decides using evidence from both sides, the law and rules, and industry codes. It is free. source

You have 6 months from the date on the final response to refer your complaint to the Ombudsman. After that it usually cannot help, unless exceptional circumstances (such as serious ill health or bereavement) stopped you, the insurer did not send a valid final response, or the insurer agrees. source