Originally Posted by jcyuhn

You really need a new, qualified, mechanic is the problem.

The VIN is the number visibile through the windshield and the drivers' B-pillar. This is what is correctly used on your paperwork.

The firewall contains the chassis number. Though similar, it is not the VIN. Any Benz mechanic worth his salt would know this. Benz cars have been identified this way for decades.