I have to replace my crankshaft (which only has 40k on it!

).
Does anyone know where the heck to find a crank for a 2.7l m20 engine. Evidently it isn't the easiest part to find.
If I could just get the reciept from where it was purchased BMW says they could exchange it for free (due to the fact that is about 6 months old and it must have been tempered wrong because the thrust bearing has acted as a metal lathe and engraved an enormous groove in it. Let me know if you have any suggestions.