The Ombudsman received 897 complaints against Bank of Scotland about mortgages and home finance.
Coming in second, third and fourth place was Santander (708), Legal & General Partnership Service and Barclays (597).
In terms of the total number of complaints for all financial products Bank of Scotland again took the unwanted mantle with 20,288 cases.
Overall complaints to the Ombudsman increased by 8% compared to the second half of 2014 with 173,994 cases, with three in five (57%) being upheld.
The number of non-payment protection insurance complaints soared by 45% to 79,550 in the first half of 2015 compared to the second half of 2014, largely due to an increase in complaints about packaged bank accounts.
PPI complaints still accounted for 55% of cases.
Caroline Wayman, chief ombudsman, said: “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.”
