My daughter recently bought a used Audi TT. It was found that a screw had come loose and dropped into the crankshaft. This had apparently happened at the dealership during a service (before she bought the car).

Oil now covers most of the engine and smoke pours out of the exhaust. They won't admit any possible damage to the crankshaft and insist that she takes the car back as it is - in their words - "fixed". Does she have to take back a car she no longer has any trust in?