Motorists believe that repairers are ripping them off by millions of pounds, according to a survey by insurer Norwich Union.

Its Fairer Deal for Drivers study of 632 motorists found that nearly 5m drivers thought that had been overcharged or received bad service in the past 12 months.

Women believe they are ripped off by an average of £100, while men claim to pay £85 too much. As a result, more than one-third of women get a man to take their car for repairs – however 25% of males claim to be anxious about visiting a garage.

Richard Alger, Norwich Union market development manager, said: “Motorists are getting a poor deal at garages. The aim of this campaign is to provide consumers with information to protect them against rogue repairers and help them identify the many good garages and mechanics that operate in the market.”

Norwich Union has produced a free guide – Fair Deal for Drivers – in association with Trading Standards in a bid to stamp out rogue repairers.

Peter Stratton, Trading Standards Institute spokesman said: “Consumer complaints regarding current malpractice in the motor trade remain our highest single cause for concern.

“This survey provides evidence of the need for urgent action to protect the consumer.”