A leading consumer watchdog is calling on Renault to improve communication with its sales and servicing network after dealers refused to recognise a fault with the manufacturers cars.

The Consumers' Association - which was behind the 'Rip-Off Britain Campaign' that majored on car price differences between UK and European new car prices - says drivers experiencing an engine fault were turned away from dealers and told there was nothing wrong with their car.

“Readers have been told by the dealer that they're unable to locate a problem,” says the association's magazine Which? “There needs to be better communication between Renault UK and all Renault dealers to ensure affected vehicles are recognised and put right. It is a problem that can be fixed but it seems that not all Renault dealers are aware of the problem and its cure.”

At the start of the year, Renault was forced to recall 4500 1.6-litre Lagunas - the first car to receive a five-star Euro NCAP safety rating. Renault discovered a software problem in the engine management unit was causing the car to stall at low engine revs when the air conditioning cut in.

Now, the consumer watchdog says it has received 23 letters from concerned drivers experiencing similar problems in Lagunas powered by 1.8, 2.0 and 3.0-litre petrol units.

It also says it has received similar complaints from owners of Renault Clios, Meganes and Scenics and highlights one from a Clio driver who claims he crashed his car after the engine cut out.

Now, the Consumers' Association wants Renault to recall all cars that could be affected by the problem. But Renault is refusing to bow to pressure from the watchdog. The French carmaker is dismissing the association's claims that it should issue a recall of all variants.

Renault, which sold 30,000 Lagunas last year, says owners having trouble with their cars should contact their local dealer. “We are happy that owners of 1.6-litre Laguna cars affected by the fault have been notified,” a Renault spokesman adds.