Take lots of pictures.
Get your "old parts"
Keep the dispute on the credit card active.
Get the credit card company involved.
Get the local attorney general involved.
This is called fraud. You were charged for work, never performed.
Call the Mercedes Hot line and get the regional service advisor to look at your car. With your reciept in hand. He will be able to tell the lack of new parts.
Get a Lawyer.
Make post here
My Doctor's Wives Group and their Mercedes'
1970 220D, owned 1980-1990
1980 240D, owned 1990-1992
1982 300TD, owned 1992-1993
1986 300SDL, owned 1993-2004
1999 E300, owned 1999-2003
1982 300TD, 213,880mi, owned since Nov 18, 1991- Aug 4, 2010 SOLD
1988 560SL, 100,000mi, owned since 1995
1965 Mustang Fastback Mileage Unknown(My sons)
1983 240D, 176,000mi (My daughers) owned since 2004
2007 Honda Accord EX-L I4 auto, the new daily driver
1985 300D 264,000mi Son's new daily driver.(sold)
2008 Hyundai Tiberon. Daughters new car