The number of complaints against advisers jumped by 27 per cent in the first half of the year, FSA data shows.
Data published by the regulator last week shows between 1 January and 30 June, the number of complaints related to personal investment firms, including tied financial advisers, IFAs and arranging intermediaries, rose from 27,525 to 34,886.
Unlike the Financial Ombudsman Service, the FSA does not split out the number of complaints that relate only to IFAs.
Personal investment firms upheld 39 per cent of the 13,374 closed complaints against them and paid out almost £31m in redress between January and June this year, up 17 per cent from £26.6m the previous six months.
Personal pension complaints increased 7 per cent from 23,099 to 24,640.
Complaints about home finance, which covers mortgages, equity release and unregulated mortgages, grew 19 per cent from 69,089 to 82,124. Complaints to mortgage businesses, which includes lenders and brokers, jumped 81 per cent from 52,722 to 95,363.
Complaints about structured products rose 34 per cent from 1,692 to 2,266 following a 40 per cent rise in the previous six months.
There were 3.6 million complaints about financial services firms in total during the first half of the year, mainly relating to payment protection insurance. Banks and building societies accounted for 2.8 million complaints.
Essential IFA managing director Peter Herd says: “The personal investment firms category is so broad it is hard to see what is really going on. I would like to see the regulator producing data which shows whether it is IFAs driving these complaints or not.”