We have a 2000 1.8T audi quattro wagon with 87k. The wheel bearings keep failing. both front bearings replaced at sbout 85K. The rear ones started going at 50K. The right rear is failing again after being replaced 2X. Have extended warranty thru AAA and have had nothing but grief obtaining service authorizations. Audi bearings have been installed by the mechanic. Anyone know if this is a common problem?