The figures show that 149,925 complaints were fired off against banks, insurance providers and finance companies during the first half of 2011, an increase of 54% on the previous six months, while just over 97,000 grievances were filed about PPI.
Lloyds TSB Bank topped the list with a total of 19,569 complaints, of which a massive 16,965 were about PPI. Barclays Bank was next with 16,864 in total, of which 12,862 concerned PPI.
Bank of Scotland was the third highest with 13,021 complaints and 9.945 about the insurance product.
Which? executive director Richard Lloyd said: “In a properly functioning market banks wouldn’t be able to get away with treating customers like this.
“Even if you take PPI out of the equation, these figures point to the blasé attitude banks seem to have towards their customers.”
He added: “If the next round of complaints data doesn’t show a dramatic improvement then the FSA must take tough enforcement action against banks whose complaints handling isn’t up to scratch.”
The FOS data also reveals details about the amount of complaints, per firm, which have been resolved in favour of the consumer.
Some 63% of the 19,569 complaints against Lloyds TSB were resolved in favour of the consumer, while 43% of the 16,864 complaints against Barclays Bank also resulted in a victory for those borrowers.
Some 85% of the total 1,007 complaints made against CitiFinancial Europe resulted in a backing for the consumer, while 65% of the total of 2,882 complaints against Clydesdale Bank was also found in favour of those consumers.
Chief ombudsman Natalie Ceeney 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.
“This period coincided with the time when most of the high street banks and some other financial businesses had put PPI complaints on hold, because of their legal challenge against the ombudsman service and Financial Services Authority.
“As a result, complaints in this period about PPI were harder fought, and harder to resolve - particularly if we found in favour of a consumer. This data therefore gives only a partial view on the cases which we were working to resolve over this period.”