Firms paid out £1.9bn in redress for payment protection insurance during 2011, according to the latest figures from the Financial Services Authority.
Figures for December 2011 show £441m was paid during that month, the largest monthly payout yet. The figures relate to 16 specific firms who accounted for 92 per cent of all PPI complaints during the first half of 2011.
But Which? says this is not enough and banks have reserves of £7.6bn saved for redress. Which? executive director Richard Lloyd said: "It's good to see PPI payout finally starting to speed up but last year's compensation of £1.9bn is less than a quarter of what lenders expect to refund.
"Too many people are finding the claims process too lengthy, the banks must streamline the process to make it easier for people to claim."
One of the reasons for the high volume of PPI redress is the popularity of claims management companies.
It is estimated by the Financial Services Compensation Scheme that £70m could be paid out in PPI redress during 2012/13.
FSCS chief executive Mark Neale urged consumers to contact the FSCS directly as claims management companies usually required a payment.
The average pay out to a consumer who contacted the FSCS via a claims management company was £4,534.
He said: "The significant uplift in PPI claims shows no signs of slowing down. The amount consumers pay to claims management companies for handling their case is sizeable.
"Claims management companies take a significant part of the possible pay-out and are no more likely to make a successful claim than consumers can on their own."