new defective VS parts warranty

I want to get some thoughts on this
GM policy ?
A bumper is sent to a body shop. the body shop sands the bumper in preparation for paint.
Before painting they notice the bumper is warped. They send it back to us for credit.
Do we claim it as new defective or do a parts warranty on it ?
thank you in advance
GM policy ?
A bumper is sent to a body shop. the body shop sands the bumper in preparation for paint.
Before painting they notice the bumper is warped. They send it back to us for credit.
Do we claim it as new defective or do a parts warranty on it ?
thank you in advance