Lloyds Banking Group was the most complained about bank during the first half of 2011, according to the Financial Ombudsman Service.

Lloyds TSB received 19,569 complaints, subsidiary Bank of Scotland received 13,021 and smaller divisions totalled a further 5,106.

This brings the total number of complaints for Lloyds Banking Group to 37,696.

A significant number of these were about PPI, 16,965 of the complaints to Lloyds TSB were related to PPI while 9,945 PPI complaints were made to Bank of Scotland.

FOS upheld 63 per cent of Lloyds TSB cases and 44 per cent of Bank of Scotland complaints in favour of the consumer. The average rate across all companies was 47 per cent.

In second place was Barclays Bank with 16,864 complaints, more than half the number for Lloyds.

Natalie Ceeney, chief executive and chief ombudsman for FOS, said the peak was due to the coincidence with the legal review between banks and the FOS/FSA which caused complaints to be put on hold.

She said: “These latest figures show a significant increase in the number of new PPI complaints referred to the Ombudsman during the first half of 2011.

“Complaints in this period about PPI were harder fought and harder to resolve, particularly if we found in favour of the consumer. This data therefore gives only a partial view in the cases which we were working to resolve over this period.”

Richard Lloyd, executive director of Which?, said: “These numbers show that some banks are still not dealing with PPI complaints fairly. Even if you take PPI out of the equation, these figures point to the blasé attitude banks seem to have towards their customers.

“If the next round of complaints data does not show a dramatic improvement then the FSA must take tough enforcement action against banks whose complaints handling is not up to stratch.”