CITY watchdog the Financial Conduct Authority (FCA) has received a record 4.13 million complaints in the first half of this year – a rise of 10% on the previous half-year period.

The regulator said this was the fourth successive half-yearly increase with the total number of complaints relating to 3161 firms and the vast majority (98%) of them directed at just 235 businesses.

Payment Protection Insurance (PPI) held its unenviable place as the most complained about product, and accounted for 42% of the total.

PPI was followed by grievances about current accounts, which notched up 15% of the total, then credit cards (8%) and motor and transport insurance, which attracted 6%.

Taking PPI out of the equation, the FCA said complaints increased by 9% (193,360) on the last six months of 2017.

There were several high-profile cases of disruption to retail banking services in the first half of 2018, which contributed to the rise in complaints to certain firms.

The FCA also noted a fall in the proportion of non-PPI complaints closed by firms within three business days.

In the first six months of this year 58% of all complaints were resolved within this time, compared to 59% in the previous period.

Christopher Woolard, executive director of strategy and competition said: “Firms need to be doing all that they can to reduce complaints.

“It is clear that firms need to look at the cause of the rise in complaints and address these issues to prevent further increases.

“It should be a priority for firms to ensure good consumer outcomes are achieved and they should be making sure that they are taking the right steps to treat customers fairly.”

Woolard added: “We are encouraged to see that figures are showing that more consumers are making a decision on whether to complain about PPI.”

The watchdog, meanwhile, has been hit with a series of staff departures as it grapples with Brexit-related issues on top of its regulatory role.

According to the Financial News website, which obtained the data from a Freedom of Information (FOI) request, more than one in nine (11.4%) of around 3700 FCA staff left in the 12 months to April this year.

The turnover figure had then risen to 11.7% in June 2018, the latest available figure, and is significantly higher than the Bank of England’s retention rate of around 8%.

It is also one of the worst retention rates since the FCA’s inception in 2013.

In the 12 months to April last year the rate fell to 10.9% after Andrew Bailey’s appointment as chief executive helped stabilise it after two previous CEOs left.

Some former employees have voiced their dissatisfaction with below-market salaries and increasing workloads.

In April, Bailey warned that Brexit would dominate the regulator’s workload – saying it had to dedicate a “high level of resource” to policing UK financial institutions’ readiness for leaving the EU and helping government transpose thousands of European laws into British law.

A spokesperson for the FCA said: “The staff turnover rate has shown little change over the last few years and we have seen no increase since our move to Stratford.”