If they can't or won't fix it, keep all your documentation such as the service report and work order, just in case it does fail. If the problem was noted prior to the expiry of your warranty, you have grounds for an appeal at that point.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue