Worst performing were the ones working for banks and building societies, where only one in every six reached the required standard in the Which? poll.
Neil Fowler, editor of Which? magazine, said: “Our latest investigation leads us to believe that the industry has failed consumers in the provision of this crucial service, and is still failing them.”
Findings of poor advice from high street banks comes amid concern that irresponsible lending and bad information is leading many to go needlessly into debt.
Although independent financial advisers were found to do better, only half reached the required standard in the survey.
However, Mr Fowler said that good advice for debt and loan problems does exist: “There are some good advisers out there but they take a bit of finding.”