Complaints to the Financial Conduct Authority dropped by 5% in the first six months of 2014, the watchdog has announced.
In total it received 2,358,732 complaints between January and June, down from the 2,493,729 complaints it dealt with in the last six months of 2013.
Payment Protection Insurance (PPI) is still the most complained about product, despite a drop of 11% in the first six months of 2014, with 1,236,899 complaints. The amount accounts for more than half (52%) of all the complaints the FCA received and 78% of complaints about general insurance and pure protection products.
Problems with current accounts were the next most complained about issue (319,505 complaints, up 3%), followed by general insurance (318,502 complaints, down 1%), credit cards (127,708, down 10%) and savings and other banking issues (89,767 complaints, up 4%).
Barclays Bank was the most complained about firm with 278,426 complaints (down 10% on the previous six months), followed by Bank of Scotland (265,640, up 46%), Lloyds Bank (264,115, up 3%), NatWest (140,342, down 20%) and Santander (135,611, down 13%).
Overall, complaints against banks and building societies accounted for 66% of all complaints it received in the first half of 2014.
The FCA's director of policy, risk and research, Christopher Woolard, said: "It's important that firms now get on top of the issues that are driving complaints.
"Although it's encouraging to see the total number of complaints fall, there is clearly further work to be done to ensure that consumer interests come first."
In response to the findings, Matt Hammerstein, head of client and customer experience at Barclays, said: "We are constantly making improvements to our day-to-day customer experience. However, our banking complaint figures reflect some significant one-off changes in the first half of 2014.
"We'll never stop striving to improve service and prevent the need for complaints and we believe this approach will deliver real change in customer satisfaction for the long term."