Customer complaints about financial firms jumped 40% to over 68,000 cases in the final quarter of last year, according to Financial Ombudsman Service data.

The disputes body received a total of 68,430 complaints between October and December, which was “a slight drop” on the 73,692 complaints reported in the previous quarter.

Motor higher purchase deal complaints jumped “almost three times” to 15,956 cases, followed by disputes about credit cards, current accounts, car/motorcycle insurance and motor conditional sales.

The service said it continued to see “high levels” of car finance cases from consumers who, “were not told the car dealer would get commission from the finance provider for arranging the finance”.

Many critics fear motor finance mis-selling could rival the payment protection insurance saga, which involved 64 million claims and cost banks around £50bn.

Complaints about home loans were further down the list.

First charge mortgage disputes came in at 1,271 cases in the period, while buy-to-let disagreements registered 199 cases.

The department adds that claims management firms, or professional representatives, continued to post “a high level of complaints, particularly around hire purchase (motor), credit cards and current accounts”.

It says between April and December last year, professional representatives accounted for around 47% of the cases it received, compared to just 21% reported in the first nine months of 2023/24.

Last month, the disputes body said it would begin charging claims management companies who bring complaints on behalf of customers for the first time.

It says these firms, who came to prominence during the payment protection insurance scandal, will be able to bring ten cases to the service for free a year.

But after that, they will be charged £250 a case from April. They will receive a £175 rebate “if the outcome is in favour of the consumer”.

Also, last month, the ombudsman unexpectedly replaced chief executive Abby Thomas, with interim chief ombudsman James Dipple-Johnstone.

Dipple-Johnstone says: “We are continuing to see high volumes of motor finance commission cases and would encourage businesses to consider whether complaints are covered by the Financial Conduct Authority’s temporary complaint handling rules.

“Ongoing legal proceedings are impacting our ability to issue final decisions in these cases, but we are putting steps in place to ensure we can resolve them as quickly as possible when we have the clarity we need.”