The ombudsman received 3,090 complaints about home mortgages in the period between July and September and has received a total of 6,031 complaints in this area this year.
FOS said 28% of these complaints were upheld in favour of the consumer, slightly above the 26% uphold rate registered in the 2012/13 financial year.
The complaints received this quarter continued to be dominated by PPI which accounted for 81% of all consumer issues raised. The ombudsman received a total of 143,177 new complaints this quarter, taking it to 247,399 for the financial year.
FCA figures released last week saw Santander crowned the UK’s most complained about lender in the first half of the year.
FOS chief executive and chief ombudsman Natalie Ceeney said: “If we listen carefully to what they are saying, those customers written off as ‘complainants’ might just be the key to matching marketing aspirations with customer reality.”