Audi TT 02 rear wheel bearing

I replaced left rear wheel bearing 18 months and 9000 miles ago and it went out again. I noticed that the protective dust cap was not on the hub, so I checked the right side and it is missing also. I figured I would go ahead and replace both rears since the right is probably on borrowed time. What about the covers? Does anyone have any experience with these. I'll probably end up getting the covers from dealer since I have not been able to locate them on-line at parts houses. Any input regarding bearing failures or covers would be much appreciated. Thanks