| Be firm and make them take the car back. Dont take No for an answer. A busy Saturday is always a good time to make a fuss in the showroom. Serious engine problems so early on are going to cause nothing but a string of problems from here on. They have obviously tried to fix it and have failed. Contact Trading Standards/Citizens advice/get legal advice.
My father had to get a solicitors letter drawn up to threaten to sue a dealer in order to return a car after 6months of endless serious engine faults. They paid out. | 
