Good lesson to read the fine print on your extended warranty.

Charging for diagnostic time when no fault is found is not limited to extended warranties, it can happen with a new vehicle warranty as well. It is designed to deal with those owners who continually request service for no obvious reason. There is usually some judgement applied as to when to charge it. For example, if the SA hears the noise, but they can't find the cause in the shop, that is not the same situation as having no evidence of any fault, ie you requesting service when nothing is wrong.

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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