Bank of Scotland, which incorporates Halifax and BM Solutions, has topped the mortgage complaints list for the fourth year running.
Bank of Scotland received 884 mortgage complaints between July 1 and December 31 2011, with 32% upheld in favour of the consumer, data from the Financial Ombudsman Service reveals.
Santander UK received the second highest number with 515 complaints, of which 26% were upheld. This was followed by Barclays with 458 and 41% upheld.
Northern Rock Asset Management received 330 complaints, with 17% upheld, while Cheltenham & Gloucester received the fifth highest number of complaints at 284 with 22% upheld.
Overall, Lloyds Banking Group received the most complaints over the six-month period at 20,310.
During this time, FOS received a total of 106,193 new complaints, 89% of which involved 163 financial businesses.
Of the cases published, 46,700 related to payment protection insurance, a decrease of 53% on the 98,632 PPI cases received in the first half of 2011.