The consumer champion says although only one in 20 private patients felt they had cause for complaint, 45 per cent of those who had formally complained were dissatisfied with the outcome.
Forty per cent did not think things would improve as a result of the complaint, and 38 per cent were dissatisfied with the level of support they received in making the complaint.
A Which? spokeswoman says: “This is compounded by the fact that private patient do not have routine independent advice and support even with higher risk services such as surgery.
“Some voluntary complaints investigation scheme for private healthcare do exist, such as the UK-wide Independent Healthcare Advisory Services, but not all organisations join such a scheme.”