Bank of Scotland received the highest amount of complaints relating to mortgages and home finance in the first six months of the year, Financial Ombudsman Service (FOS) figures show.
A total of 563 complaints were received about the bank between 1 January and 30 June, 40% of which were found in favour of the consumer.
This is the first time the FOS has named financial companies' complaints records. To qualify, the FOS had to receive at least 30 new complaints about the firm and resolve at least 30 others in the six-month period.
Barclays received the second highest amount of mortgage complaints with 371, 55% of which were upheld, while Abbey received 299 complaints, 52% upheld.
Nationwide Building Society, Cheltenham & Gloucester, Alliance & Leicester and Northern Rock also made the list.
In terms of the highest percentage of complaints upheld, GMAC-RFC topped the list with 75% of its 53 complaints found for the consumer, while 60% of the 47 complaints against GE Money Home Lending were upheld.
Walter Merricks, outgoing FOS chief ombudsman, says: "[Naming firms' complaints records] will help people to see how the financial businesses that are responsible for nine tenths of the ombudsman's workload deal with customer complaints.
"This should mean fewer of their customers having to bring unresolved complaints to the ombudsman."
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