Bank account complaints jump by a third, reports FCA
The number of people complaining about their current accounts jumped by a third in the first half of the year, the financial regulator has said.
There were 506,326 such complaints between January and June, a rise of 31.2% on the previous year.
The Financial Conduct Authority (FCA) warned the banks to take action to address the problems.
But the industry said it had already stepped up efforts to reduce the number of unhappy customers.
Many have been complaining specifically about packaged accounts, which include insurance policies.
Banks charge a monthly fee for such accounts, but some people say they have been signed up without their permission - or have found the insurance products worthless.
"This is the second half-year running that we have seen complaints about banking products rise," said Christopher Woolard, the FCA's director of strategy and competition.
"It is clear that firms need to look at the causes for this rise, and where necessary take action to address the causes of the trend."
Last month the Financial Ombudsman Service - which handles complaints that cannot be resolved - said that the number of people unhappy about their packaged accounts had "shot up".
It said it was handling 1,000 complaints a week.
In the first half of 2015, Barclays received the most complaints about banking and credit cards - more than 140,000.
NatWest Bank received nearly 96,000.
In response, the banking industry said it was reacting quickly to the increase in the number of complaints concerning packaged accounts.
"Banks have redoubled their efforts to ensure that any packaged account bought by a customer is right for their individual needs," said a spokesperson for the British Banking Association (BBA).
The total number of complaints about financial services firms fell by 2.1% in the first half of 2015, due to fewer complaints about Payment Protection Insurance (PPI).