Pads I can believe( but that sounds a little early), But the rotors should last through about 3 sets of pads. I would pay for the rotors but I would also inquire about a possible caliper problem that may be causing the pads to stick and the heat build up has warped or dammaged the rotors. Otherwise the rotors should not need replacing. We have a 99 E300 with 63,000 mi and the rotors are fine. I measured them when I replaced the pads at ( second set) 55,000 mi and they should last to about 90-100,000 mi.
IF they are replacing rotors at such a low milage. Items covered under warrantee are defective and the whole system should be looked at.
I would suggest that any Item that you have to pay for that is being replace. Demand that the old part be returned to you once it is off the car. If you had the rotors you could have them measured and see if they are telling the truth. It keeps them honest. If they DO need replacing then something is wrong with the braking system. Demand further investigation of the car.
Mercedes does not turn rotors. It is cheaper to replace them
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