Lloyds Bank, Bank of Scotland and Barclays were the three most complained about banks in the first half of 2014, the Financial Ombudsman Service has revealed.
Some 30,768 Lloyds customers escalated their complaints to the Ombudsman after the bank failed to adequately address their concerns.
During the period, 27,883 dissatisfied customers of Lloyds' sister bank Bank of Scotland did the same, as did 26,955 Barclays customers.
All in all, the Ombudsman received 191,129 new cases in the first six months of 2014, with payment protection insurance (PPI) accounting for 70% of them.
Lloyds Bank, Bank of Scotland and Barclays appeared in the same order for PPI complaints, as they did for overall complaints.
For Lloyds, 85% of the complaints taken to the Ombudsman were to do with PPI, while at Bank of Scotland the percentage was slightly higher at 86% and at Barclays it was 82%.
The Ombudsman received 1,062 complaints about Bank of Scotland's home loans during the first six months of the year, with Santander's triggering 753 and Barclays 503.
Overall, the number of complaints taken to the Ombudsman was 3% higher than during the second half of the 2013 at 57,310, compared to 55,747. There were 7% more banking complaints and 1% more insurance cases.
The Ombudsman sided with the consumer in 57% of cases, up from 51% during the previous six months - meaning the banks were treating customers worse.
Caroline Wayman, chief ombudsman, said: "We're seeing more and more people turn to us in frustration where they feel their bank or insurer simply doesn't understand or really care. And we're hearing growing dissatisfaction from people about being processed industrially as a number rather than being listened to as an individual customer.
"By giving their customers more thoughtful, considerate and personal responses - clearly setting out the reasoning behind an individual decision – we know that businesses can help sort out problems earlier on, prevent complaints being escalated to the ombudsman and rebuild trust and confidence more generally."