The Financial Ombudsman Service (FOS) saw a near-60% rise in complaints relating to payment protection insurance (PPI) in the final three months of 2011.
According to the BBC, the Ombudsman received 30,301 PPI complaints in the final quarter of last year, 57% more than the 19,259 received in the previous three months.
Of these, the FOS found in favour of the customers in 68% of cases.
The rise led to a 10% increase in the total number of cases dealt with by the Ombudsman in Q4, which received a total of 55,907 complaints in the period.
Payment protection insurance complaints now make up 54% of the FOS's entire workload, far outstripping complaints related to other products.
Credit cards, current accounts and mortgages between them accounted for just 18% of all complaints received between October and December last year.
Earlier this month, the FOS proposed a new funding system for firms that receive a large number of complaints.
The "largest users" of the FOS refer more than 2,000 cases to it each year.
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