My 2000 CSVT had the same problem straight from the factory! There are two screws that are supposed to hold the sides of the rear cover inboard. The screw heads, on mine, were busted right off. I think perhaps they broke mine during rail transport from the factory to the dealer. Anyways, I just recently fixed them myself.
One day while I had the rear wheels off, I removed the other lower screw that holds the bumper to the plastic wheelwell liner. Then I needed to use needle nose pliers to turn the broken piece of screw out of the bumper covers retaining clip. The bumper is flexable enough to actually pull it out and see what's going on. Then I just put it back together with new screws. Hope this helps.
