The FOS received a high of 127,471 new complaints last year, with only 3,824 complaints against advisers, down from 4 per cent in 2007/08.
A spokeswoman says only 30 per cent of complaints against IFA firms were upheld.
She says: “The uphold rates for IFAs are much lower than for other areas.”
Banks were the cause of 59 per cent of complaints, life insurance and investment providers 11 per cent, general insurers 13 per cent, general insurance intermediaries 5 per cent and mortgage intermediaries 4 per cent.
Complaints about investment-linked products more than doubled to 5,798 from 2,750.
FOS chairman Sir Christopher Kelly says: “As the credit crunch leads to increased financial difficulty for many consumers, we are gearing up to deal with further volatility in complaint volumes.”
Yellowtail Financial Planning managing director Dennis Hall says IFA complaint numbers are so low because they focus on building long-term relationships.
He says: “Advisers have been much quicker to embrace fees and customer-agreed remuneration structures where they generate recurring income on the services they deliver and the long-term relationships they develop with clients.
“Banks have a high turnover of staff and are unlikely to try to form long-term relationships with clients and their focus is on sales volumes and turnover.”