The UK's largest free mediation website has predicted a surge in complaints about pensions as it reaches its two millionth customer.
Resolver launched three years ago to allow people to make complaints about a range of services for free and direct to the business.
The most complained-about product over the past three years has been payment protection insurance, with 784,945 complaints.
But Resolver is predicting a "significant rise" in complaints about pensions as well as a big increase in complaints about mortgages.
James Walker, founder of Resolver, said: "It’s extraordinary that over two million people have used Resolver to sort out a complaint in such a short period of time.
"Clearly, more people are making their voices heard about the things that make them unhappy – but the businesses that are listening to complaints and acting quickly are reaping the benefits, as customers tell us they are far more likely to stay loyal if treated fairly."
The second most complained-about product was flights, with 291,318 complaints followed by packaged bank accounts with 204,231.
The company has been in a partnership with MoneySavingExpert and its founder Martin Lewis for the past two years.