Lloyds Banking Group received the highest number of complaints from UK customers in the first half of the year, according to the Financial Services Authority (FSA).
The state-backed bank received more than 280,000 complaints in the first half of the year. Second was Barclays, which received 259,266, closely followed by Santander, receiving 244,978.
While Santander received fewer complaints it was the worst of the banks for dealing with complaints within the benchmark time period of eight weeks. Only 46% of Santander cases were closed within this time frame.
Lloyds, on the other hand, dealt with 97% of complaints within eight weeks, and Barclays dealt with 91%.
As the largest bank, Lloyds is statistically more likely to receive complaints. Its customers hold 72 million products, and fewer than 1% of its 30 million customers complained.
A spokesperson for Lloyds says: "Our relationship with our customers is at the heart of our business and we take all feedback very seriously.
Like every organisation we know there are areas where we can improve and we're working with our customers to do just that.
"The vast majority of our customers are happy with the service we provide and this is reflected in the low number of complaints we receive relative to the high number of accounts our customers hold."
Separate figures from the Financial Ombudsman Service (FOS) show it upheld 61% of complaints against Barclays in the first half of the year, compared to 45% of complaints against Lloyds. The FOS only upheld 19% of Santander complaints.
The FSA is proposing changes to the way in which complaints are dealt with. These measures include forcing banks to send customers letters explaining that if their complaint was not upheld, they can challenge it through the FOS.
They will also be required to make a senior manager responsible for the handling of complaints.
Sheila Nicoll, the FSA’s director of conduct policy, says: "Good complaints handling standards should be the rule not the exception and complaints handling forms a key part of our intensive and intrusive approach to supervise how firms deal with their customers."