Anna went to look at a Ford Escort, advertised privately in her local paper. She asked the seller if the car had been in an accident. He said no, but having bought the car, Anna later found evidence of major crash repairs. She went back to the seller, pointed out the car was not as described and eventually got her money back.
However, if the car had just been unreliable (even breaking down on her first drive), there is probably little she could have done, as there is nothing in law that states that a car bought privately must be of satisfactory or reasonable quality.