The Financial Ombudsman Service has been accused of treating advisers as "guilty until proven innocent" in a survey of IFAs.
The survey, carried out by Panacea Adviser, found 83 per cent of advisers felt the Fos rules and process put an adviser in a position of having to prove their innocence, rather than the complainant having to prove the adviser was in the wrong.
Meanwhile, 60 per cent of advisers felt Fos adjudications were unfair and 66 per cent believed adjudicators or ombudsmen were helping complainants create complaints where none existed.
It comes after the Fos faced accusations of bias in a Channel 4 Dispatches documentary which led to a review by former Which executive director Richard Lloyd.
The bias in this instance was against consumers, and the review by Mr Lloyd found there was no evidence of the Fos exhibiting favouritism towards financial institutions.
Derek Bradley, founder and chief executive of Panacea Adviser, said what had struck him most was the fact the results were little changed on the previous surveys he had done on this issue.
He said: "It is clearly the case they are having some issues with this. If it is based on fact or if it is perception, then it is down to the Fos to correct that.
"The first thing the Fos should do is to create some transparency in the process and at least part of that transparency should be to meet with the trade bodies and have an open discussion about how this works.
"The people who are most sensitive to Fos decisions are small financial advice businesses because for a lot of them it is very personal."
The survey also found 80 per cent of advisers felt it was unfair they were not able to enjoy the protection of a long stop, which would place a limit on the time period after which a client could complain about the advice they were given.
In the Financial Advice Market Review, the Financial Conduct Authority ruled out the introduction of a 15-year long stop limitation period on complaints to the Fos because it found very few complaints actually fell into this category and an even smaller number were upheld.
But the regulator said that as part of the review of the FAMR in 2019, the FCA and HM Treasury would consider "any ongoing trends and the impact of the [Fos's] complaints data relating to advice on long-term products".
In response to Mr Bradley's comments about the need to engage with the industry more, a spokesman for the Fos said: "The Ombudsman organises and takes part in roadshows, exhibitions and events across the UK.
"This is part of our commitment to share our knowledge and experience with the outside world, helping to prevent complaints and encourage consumers and businesses to settle problems themselves.
"We engage with trade bodies frequently including through our twice-yearly industry steering groups, regular bilateral meetings, and maintaining constructive working relationships throughout. We also engage directly with IFAs across the country throughout the year, through a series of roundtable discussions, in conjunction with the Financial Conduct Authority."