The number of complaints about payday loan companies soared by 178% in the year to March, the Financial Ombudsman has revealed.
That is despite the fact that new controls on lenders were brought in by the regulator several months earlier.
There were 3,216 complaints about short-term loans in 2015/16, compared to 1,157 the year before.
However Payment Protection Insurance (PPI) remained the most complained-about financial product.
There were 188,712 complaints about PPI over the year, a drop of 8% on 2014/15.
Complaints about packaged bank accounts - where customers pay a fee, but enjoy benefits like travel insurance - more than doubled to 44,244.
Claims management companies, rather than individuals, were responsible for filing most of them.
The main complaints about payday lenders involved:
New controls on payday lenders were brought in by the Financial Conduct Authority (FCA) in January 2015.
After that date, interest charges were capped at 0.8% per day of the amount that was borrowed.
Stricter affordability checks were brought in a year before that, in 2014.
As a result of the new controls, and bad publicity, many payday lenders left the market.
Complaints about pet insurance also rose during the year, by 38%. Among the issues that caused disputes were: