IF (and it may be a big if) it is the same as the 1999 A4 you need to remove the carpet in the boot, you will see some bolts (on my A4 two of these are attached to the luggage hooks), these are in a straight line about a foot or two in from the outside of the car. Undo all four bolts.
Then go to the rear wheel arch and remove the screws around the rear edge, taking off the mudflaps if fitted.
Once all the screws are removed the sides of the bumper to edges should pull away from the side of the car (they kind of pop into the side of the rear wing).
Once all this is done the bumper should pull off towards the back of the car.
I wrote this as no-one else had replied. If in doubt do try phoning an Audi garage for advice - if you speak to the service department you stand a chance of getting some decent advice. If you do it yourself just take it easy and don't pull too hard on the bumper - I am assuming that the fittings are the same as my A4.
Hope this helps.
Greg
