Write a letter rejecting the car under the 30 day term of the Consumer Rights Act 2015 and previous legislation and case law and send it to the dealer principal of the dealership concerned by Post Office Special delivery demanding the return of your money and stating that you will return the car to the dealership on as specific date a few days hence. Keep a copy of your letter and staple to it the Certificate of Posting to prove that you rejected the car within the 30 day period. If the dealer challenges your rejection it will be a County Court test case under the new law. Consumer rights are here: www.honestjohn.co.uk/faq/consumer-rights/