I have recently replaced my original rear big bumper with a new aftermarket unit.  When I spoke to the garage I was told that the aftermarket bumper they used was virtually identical to the vw original so I agreed to got with that as it was a lot cheaper fitted.  Now when you look at it on the car it looks like it is sagging where it comes around the sides and as a result appears to be about 3/4 lower than it should be.  Is this likely to be just the fitting or is it possible that the bumper just badly shaped?