Manufacturers and retailers are blaming each other over a survey that says some franchised dealers mislead car owners by claiming their new car warranty will be invalid if they go to an independent company for service work.

Privately, carmakers express anger that dealers are giving false information to consumers, either deliberately or because staff are poorly trained.

The Office of Fair Trading insists: “Dealers should tell customers they can shop around, and are not tied to the main network.” Alan Pulham, RMI franchised dealers director, blames manufacturers: “They must make new car warranty conditions clear to dealers – some are still not getting the information they need.”

Twenty dealers from each of 10 manufacturers were surveyed. BMW and Citroen, named as the two most serious offenders, say main dealers will again be reminded about revised block exemption rules which encourage price competition by opening up the servicing sector.

Ford is “disappointed” by the findings. It says documents with new cars explain the warranty and hopes dealers will ensure staff give out correct information.

Seven BMW dealers said servicing work outside the main network would invalidate the warranty; four others said it might. BMW GB says it recently re-issued a reminder to its dealers that owners asking for advice should be told they are free to shop around for servicing.

Six Citroen dealers said servicing outside the network “would make the warranty invalid”, five claimed “it would be put at risk” (corresponding Ford figures were five/two).

Toyota fared best, with 16 dealers saying “take your car anywhere”, while VW, Vauxhall, Peugeot, Honda, Nissan and Renault also achieved better results in the What Car? survey.

Peter Chandler, partner in Bristol-based Citroen authorised dealer Citrotech, says: “Some dealers have idiots who answer the phone. We give a personal service, save customers up to 70% on servicing work and don’t charge for minor work.”

Tom Dunn, chief executive at Nationwide Autocentres, the UK’s largest independent service/repair network, says: “The survey findings are consistent with my experience. We service thousands of within-warranty cars each month for the fleet and contract hire sector and fully comply with the regulations.

Retail customers do not appear to be benefiting from the advantages of choice in the same way as fleet operators.”