If you bought the car within six months and something failed, the legal assumption is that it must have already been failing or starting to fail on the date you bought it and, to absolve himself of liability for that, the dealer has to conclusively prove that it wasn't. Beyond six months you have to prove the fault was present or developing on date of sale. See: www.honestjohn.co.uk/faq/consumer-rights/ If you want to speak to someone else, try Citizen's advice, but be aware that a specialist solicitor will probably charge upwards of £200 an hour + VAT.