If you do go to the dealer with your registration and ID
(as proof of ownership) and order a key and tumbler assembly
for your VIN number - you will not regret it.

Cost for me was $80 at a dealer in Thousand Oaks California.

What I recommend staying away from are locksmiths - unless
they understand Mercedes.

My car had locks and ignition replaced by a locksmith and none of the keys matched.
It was a nightmare.

__________________
80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250