The headlight haze, in most cases, can be taken care of with the 3M Plastic Cleaner, had the same thing on mine and the stuff works. As for the engine problem, scratches etc, that stinks. Fortunately I know the service manager where I bought my Xfire, he's a customer of mine. I'll make sure we walk around the car before they work on it, if they work on it. Perhaps that's a way to make them aware that the car didn't come in with any scratches.
Hope things work out for you.
Pat