I am not sure why he thought the clock spring was the problem with an airbag light. Clock spring issues I believe would trigger a BAS/ESP light. Is he reading the car as a SLK320 with the STAR/DAS or whatever it is called? I've had luck with the Autel MD802 reading all codes even some better than a DRB3 emulator. Others I believe have had luck with the CRP 123.

Not telling us what codes he is reading does not give us enough info.