Did you buy privately or from a trader?
The car should be of satisfactory quality and fit for purpose. If not, as is the case if your representation is accurate, then you can under the consumer rights act request a full refund.
You have a legal right to do this but you must do so within 30 days of the date of purchase.
The trader may try to swerve this and say your are only entitled to request that they repair the vehicle, if it still needs repair. You do not have to accept this provided that you reject the car as unsatisfactory and unfit for purpose within 30 days of the date of purchase.
In addition you can claim the out of pocket expenses from the trader. If the trader refuses you could potentially bring a claim in the small claims court.