Originally Posted by jpkirk

Any time one does a "power shift" it accelerates wear and tear on the drive train. Probably more clutch/CSC than anything else. At minimum, there is slightly less life left in those two items. Depending on how many times the tech did it, could be considerable loss of lifetime in those items. If it's working fine though, not sure what recourse you have other than what you have already said, never let that guy see or touch your Z again.