PPI is still the most complained-about financial product, new figures from the Financial Ombudsman Service show.
The ombudsman started work on 188,712 new PPI claim cases last year and is still receiving up to 4,000 new cases every week.
Of the three million or so cases received by the financial ombudsman since 2001, about half have been about PPI.
In total, the service had 1.6m initial enquiries from members of the public in the 2015/16 financial year, of which one in five – 340,899 – became formal disputes.
The ombudsman resolved 438,802 complaints, with around half upheld in the consumer’s favour.
Complaints involving credit, such as hire purchase and point of sale loans, increased by 40% and payday loan complaints tripled – a huge 178% rise.
Specialist insurance complaints rose, with pet insurance (38%) and home emergency cover (37%) both increasing by more than a third and warranty complaints increasing by a fifth (20%).
But credit broking complaints fell by half (54%) and annuity complaints remained stable.
The ombudsman said the figures show people’s growing awareness of their rights when things go wrong, adding that nine in 10 people now know about the financial ombudsman.
Chief ombudsman Caroline Wayman said: “It’s been another year of big numbers and big changes for everyone. But we mustn’t lose sight of the lives and livelihoods behind every complaint we resolve.
“That’s why preventing mistakes of the past from happening again will help restore trust and fairness in financial services.”
Analysis of the ombudsman’s figures shows that four of the UK’s largest banking groups accounted for 56% of all complaints received.
People from Warrington were the most likely to phone the ombudsman and consumers from the north east were more likely to complain about PPI.
Earlier this month, the Public Accounts Committee warned that consumers were still at “serious risk” of being mis-sold financial products.
The committee also criticised the process that has allowed claims management companies to make up to £5bn from PPI claims.
It said that despite consumers being able to claim compensation directly through the ombudsman, more than 80% of complaints made in 2014/15 were through third-party companies.