The majority of homeowners who challenge demands from lenders for higher mortgage repayments following calculation errors are winning their cases, it emerged.
The Financial Ombudsman Service said it had handled around 50 cases in the past three months in which borrowers had been told they faced a shortfall on their mortgage due to errors made by lenders in calculating their monthly repayments.
In most cases, lenders demand the shortfall is made up, either through a lump-sum payment, higher monthly repayments or by extending the mortgage term.
But the ombudsman said in the "majority" of cases that were referred to the service, it had found in favour of consumers as they were not in a position to know that they had been paying the wrong amount, meaning lenders have to write-off the shortfall.
The issue came to the fore in July this year when it emerged that 18,000 Yorkshire and Clydesdale Bank customers were facing a shortfall on their variable rate mortgages after the bank miscalculated their monthly repayments.
While around half of the customers - some 9,000 people - were asked to pay an increase of less than £25 a month, the rest faced soaring repayments of up to £300 a month.
The Ombudsman could not comment on whether the recent cases it has handled related to Yorkshire and Clydesdale Bank.