This was down from the 7,469 complaints it recieved in 2009/10 and 7,602 in 2008/09.
However, the FOS reported an increase in the number of complaints from consumers whose applications to port their residential mortgage had been declined.
It said that in some cases this was a result of the lender tightening its criteria and the borrower failing to meet them.
It added that in cases such as this, it may decide that a fairer outcome would be for the lender to waive an early repayment charge rather than allowing the loan to be ported.
The FOS also saw claims where a lender had reduced the upper age-limit applying to the term of a mortgage or to require the consumer to provide proof of retirement income.
There was a fall in the number of investment-related complaints across almost all product areas with the largest drop in the number of mortgage endowment complaints – which fell by a further 44%.
However, new cases for the Financial Ombudsman Service (FOS) soared by 26% in the year to March 31 2011, driven by a record number of complaints about PPI mis-selling.
The FOS received a record 206,121 new cases, which was 8.5% higher than expected.
This was largely as a result of a 113% rise in the number of PPI cases, following a 56% hike the previous year. Total complaints about PPI soared to 104,597; the largest number of complaints the FOS has ever received about a single product in one year. Complaints about the product made up half of the total caseload.
The FOS resolved 164,899 cases, which was fewer than planned because of the legal action taken on PPI complaints.