A leading debt advice charity says it has seen a big rise in the number of clients with payday loan problems.
StepChange Debt Charity says nearly 67,000 people asked for its advice last year about dealing with the loans.
That was an 82% increase on the numbers it saw in 2012.
The charity has called on the Financial Conduct Authority (FCA) to impose "substantial reform" on the industry when it starts regulating personal lending in April.
"The industry has failed to address the problems causing untold misery and damage to financially vulnerable consumers across the UK," said Mike O'Connor, chief executive of StepChange.
"We hope the FCA's proposals will address some of the areas of consumer detriment, but on issues such as affordability checking, rollover and repeat borrowing, there is an urgent need for even more radical reform."
When the FCA starts regulating consumer credit organisations in April 2014, it will have to enforce a new responsibility to cap the interest rates that lenders can charge.
It is also planning to stop lenders rolling over loans more than twice, and will restrict the use of continuous payment authorities that are used to ensure repayment by borrowers.
The charity said that among those who had asked it for help, the average client had three payday loans each, with an average overall debt of £1,647.
It pointed out this was more than the clients' average net monthly income of £1,381.
A significant minority of clients, it said, had taken five or more payday loans, and the position of borrowers had often been made worse by the terms of those loans.
"We continue to see numerous cases in which debts are excessively inflated through the application of interest and charges," the charity added.
But Russell Hamblin-Boone, chief executive of the Consumer Finance Association (CFA), a trade body for some payday lenders, suggested the situation was not as bad as the charity was suggesting.
"Data from CFA members shows they receive less than five complaints, upheld or otherwise, for every 1,000 loans," he said.
"Independent research shows 94% of their customers pay back their loans on time, but we will continue to fund and work with debt advice agencies to help people who get into financial difficulty," he added.