Customers are experiencing retrospective charges for non-disclosure - a demand which might not even have legal justification.
Car insurance firms are hiking premiums retrospectively on customer disclosures of previous driving offences - with the increased prices sometimes extending back for years.
An investigation from the Guardian newspaper has also revealed that it is unlikely that such customer non-disclosure, for speeding fines and other penalties, legally entitles insurers to ask for more money.
Helen Hernandez-Sanchez claims that she was charged an extra £518 for four years of using Diamond's insurance without having informed them of her two speeding fines from 2004 and 2005. "I was aware you had to tell them about motoring convictions but this was a fixed penalty, not a court appearance," she said.
"I realise now this was a mistake. If it had been on purpose, I would not have told them at all."
Commenting on the case, Diamond told the newspaper that their policy of retrospectively charging was supported by the Financial Ombudsman. "This is a policy we have always had," it added. However, the Ombudsman said that the policy was, in fact, "not something we recognise".
A spokesperson commented: "A non-disclosure problem without a claim is a very unusual scenario. We have not issued any guidance on this specific set of circumstances."
Michael Whitton, a solicitor at law firm Edwin Coe, also said that non-disclosure of the charges "does not automatically [cancel] the contract of insurance". He added: "I do not consider Diamond has an entitlement to recover premiums for previous policy years where they say premium would have been higher had it been aware of material facts which were not disclosed."
