If the dealer will not immediately refund the money you have to keep the car, immobilise it so it can't be taken away, then pursue the matter through the small claims track of the county court. You lose the use of the car and the use of your money until the case is settled and the dealer pays, which he might not do even after the court order. Law here: www.honestjohn.co.uk/faq/consumer-rights/ If you can get the CPS interested, the threat of a criminal case against the dealer might be more likely to get your money back than a civil case.