Complaints over payment protection insurance tripled to more than 30,000 in the 2008-09 financial year, according to data released by the Financial Ombudsman Service.

PPI covers borrowers against the risk of missing payments if they lose their job or fall ill, but customers have become angry over a recent rise in prices and questionable sales techniques in this sector.

"[PPI complaints] account for about a quarter of our work at the moment," said a spokesman from the Financial Ombudsman Service.