Had same problem with a dodgy ign key for my E36. Locksmiths said they could transfer the data to the chip in a new blank BUT when I tried it, data only allowed me up to ignition dash light phase (engine won't turn over). Only option was to ring Jeff Grey on Hutt Road supply vehicle info & ID then got new key from Germany...
Key arrived in a week, programmed at Hutt Road & problem solver.
Cost $373.28
Oh yeah....locksmith refused to have anything to do with BMW after refunding key...