I had drivers rear arch of my 2001 CLK55 done as goodwill a couple of months back. Just a small bubble on the inside lip.
To qualify you need the following.
1) Have owned the car for 6 months or more
2) Have good service history, does NOT have to be MB (mine has 6 stamps, 4 MB and 2 Indi)
3) Car under 8 years of age
4) Paint depth must be under 100 Micros around the affected area. An assessor will measure before signing off on the work. If its had any accident damage the paint will probably be up in the 200 Microns.
Mine qualified no problem and the work was done ASAP with no quibble plus I was give a loan car FOC. Note they are very strict on the above criteria, Peterg1965 on here tried and his claim was turned down (they did offer to pay a share) because he had not owned the car 6 months.