Damaged substitute parts used on car fix by body shop?

I had our car repaired after an accident and the auto shop used a used rear gate which I was aware of but when I picked the car up I noticed some number of regions of chipped paint that had been repainted in our cars color and some number of long one two inch cuts in the metal below the rear window that had also been covered in paint. I complained because the used rear gate they got clearly had chipping paint and for some reason scrape marks on it. I was told most likely from them removing the window, and also the plastic decorative part was all scratch up that surrounds the back plate. What can I do? Since it's damaged can I insist on a new one they said they could sand and repaint but I'm worried about the long knife marks. will that sand out? Plus why in the hell did not the do that in the 1st place I could think for 6500 dollars they could handle that.

Honestly, I could not agree to a used substitute part unless I was to examine and OK the part myself, but you may want to be happy that they're wanting to make it right by sanding and repainting, it should cure the marks you see.

UNACCEPTABLE,If you took the car to a reputable auto body and paid big bucks for fix it should have been done with all new parts.If this was an insurance assert and they have not paid the bill I could show them exactly what the repairs appear like and refuse to pay them You may have to get a lawyer.Vehicles are to darn costly to let someone half a s their work.But If you told them to use used parts to save money then I think you can be stuck.They on occasion use after market parts in place of original,I could at least thought they could have went that way.