Complaints to the Financial Ombudsman Service (FOS) shot up by a quarter last year, with over half of the complaints relating to payment protection insurance (PPI).
This is the highest number ever received about a financial product over this time scale.
There were 105,000 complaints about the mis-selling of PPI out of a total 206,000 complaints received for the last financial year.
Natalie Ceeney, chief executive and chief ombudsman, says the ombudsman's workload has been "dominated" by PPI and this year was the busiest in the last 10 years with over 200,000 disputes and a million front-line enquiries.
Last week the banking industry pulled out of the appeal to overturn the High Court ruling on the mis-selling of PPI. The Lloyds Banking Group was the first institution to back down, prompting other high street banks, headed by the BBA write out, to follow.
Sarah Brooks, spokesperson for Consumer Focus, says the FOS should be commended for helping so many customers with complaints this year.
"The banks' battle to dodge its PPI responsibilities has damaged the industry's reputation, tied up the Ombudsman's resources and worst of all left consumers out of pocket and out of patience. We now urge banks to deal promptly with PPI complaints so consumers are not forced to go to the Ombudsman and a line can be drawn under the whole sorry affair," she adds.
There was a 30% drop in complaints about investment and a 9% fall in complaints about banking, but an increase in those about specialist insurance.
Complaints about mobile phone cover and identity theft insurance, consumer credit deals and car and travel insurance were all up.
In total 51% of complaints resolved by the FOS were settled in favour of the customer.
Were you mis-sold PPI?
If you answer yes to any of the following questions you could be able to make a claim:
Was it made clear to you that the PPI was optional?
If you feel you were forced to take out cover then you could have been mis-sold.
Was it explained to you that past medical conditions mean you are not fully covered?
Many policies do not cover existing medical problems so if you have to be off work due to an existing problem your PPI may not pay out.
Were you unemployed at the time you took out the PPI?
Most PPI policies include unemployment cover. If you were unemployed or retired at the time then this cover is of no use to you.
Were you self-employed when you took out PPI?
To have made a claim for unemployment if you were self-employed you would have had to declare yourself bankrupt or notify HMRC that you have stopped working.
Casual workers and those working on short term contracts also would not be eligible to claim. If this wasn't made clear to you, you could be entitled to claim.