Clamping cars parked on private land should be made illegal in England and Wales, according to the AA.
The motoring group claims one in 10 drivers has been clamped or fined by private enforcers, with no independent arbitration process.
It argued government proposals for greater self-regulation would not work.
The AA also said the prevalence of "bad and immoral practices" among private parking firms in England and Wales was "shocking and unacceptable", with some people being charged more than £500 to retrieve a towed car.
However, the British Parking Association countered that the AA had not come up with a "credible" alternative, but said it would welcome working with the group.
Patrick Troy, chief executive of the BPA, said its code of practice for member companies was "a good first step to improving standards", but conceded more government action was needed.
"Our scheme is not perfect and we would welcome working with the AA further on the concerns they raise in their consultation response as we are sure positive solutions can be found by working together," he said.