The most complained about product was payment protection insurance - insurance on loans - with banks having already set aside about 20 billion pounds ($32 billion) to pay compensation for mis-selling the product.
There were 278,426 complaints about Barclays, down 10 percent on the first half of 2013, while Bank of Scotland received the second-highest number of complaints, up 46 percent to 265,640 over the same period.
"It's important that firms now get on top of the issues that are driving complaints," said Christopher Woolard, director of policy at regulator the Financial Conduct Authority.
"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." (Reuters)
