The firm received a total of 897 complaints relating to mortgages and home finance in the six months from 1 January to 30 June, but is a 10% fall on complaints in the second half of 2014.
The Ombudsman’s figures showed that Santander was the second most complained about business in the mortgages and home finance category in the first half, receiving a total of 708 complaints, a 19% increase on the same period last year.
Legal & General followed with 620 complaints in the same area, with Barclays receiving 597 and Nationwide at 396.
The Ombudsman said the data covered financial businesses only where it received at least 30 new cases and resolved at least 30 cases in the six-month period.
According to FOS’s data, a total of 173,994 complaints cases were taken on by the Ombudsman – an increase of 8% compared to the second half of 2014.
While new complaints relating to PPI fell by 10% compared with the Q2 2014, complaints about financial products excluding PPI jumped by 45% to total 79,550 in the first half.
The Ombudsman said the increase in complaints was largely linked to a rise in complaints about packaged bank accounts and claims management companies during this period.
Overall, Bank of Scotland tallied up the highest number of new complaints at 20,288, followed by Barclays which received 20,021, and Lloyds Bank at 19,818.
Chief ombudsman Caroline Wayman said: “Complaints about PPI continue to make up over half of our workload. And though the number of new PPI cases has reduced in the first half of this year, the decline has not been as steady or as marked as generally expected. This is at least in part due to the continued high levels of activity by claims managers in this area.
“Claims managers have also been largely responsible for the substantial increase in complaints about packaged bank accounts, which have driven up our banking workload over this period by two thirds,” she added.
“Nobody wants “another PPI”. This is why we’re working closely with businesses, claims companies and their regulators, to make sure PPI is sorted as fairly and as quickly as possible for everyone involved – and that lessons are learned to prevent anything like this happening again. If we can all achieve this, then the next seven years should be a different story.”