Complaints to the Financial Ombudsman Service about mortgages were down by 6% from 8,421 to 7,802 over the year to April compared to the previous year.

However, enquiries about mortgages, including those that did not progress to a case being opened, were up by 5% over the same timeframe, from 9,540 to 10,043.

It comes as overall complaints about the banking sector hit a 10-year high, up by 29% from 61,995 last year to 80,137 for 2023/24.

Within the mortgage sector, the number of new complaints fell for most product types, including residential and second charge loans with a slight increase in cases about buy-to-let and equity release.

The percentage of mortgage cases that were upheld in favour of the consumer was 28%, unchanged from last year.

This compares to an uphold rate of 37% across all types of financial product.

Current accounts were the most complained about product, followed by credit cards, car finance and car insurance.

Across all categories, increasing levels of complaints are being brought by claims management companies (CMCs), accounting for a quarter of all cases in 2023/24 compared to 18% in the prior financial year.

FOS says it has seen good and bad practice from claims firms:

It says: “Some representatives submit mass claims without determining whether they have merit, whilst others fail to respond to requests for evidence slowing down our investigations.

“When complaints are upheld, professional representatives can take a significant proportion of redress awarded to their clients.”

Under new proposals designed to reduce spurious mass claims, firms could be charged up to £250 to bring a case, reduced to £75 if the complaint is upheld in favour of the consumer.

Deputy chief ombudsman James Dipple-Johnstone says: “While [claims firms] have an important role to play in resolving financial disputes, they can also gain financially from our service without contributing to the running costs. 

“There is sometimes little evidence of due diligence by some representatives to ensure claims they advance have merit.

“We are committed to making sure our service is as accessible as possible, while ensuring it remains free for all customers and that those with upheld complaints can keep all of any reward we make.

“Our proposed charges aim to ensure we cover the costs associated with resolving disputes while reflecting a fairer allocation of those costs.”