I was replacing my OEM pads with Rotex pads today and boy did I get a surprise. The car is a 2005 with a little over 20,000 miles. I had normal wear on the pads BUT I had to replace all 4 rotors. They were out of tolerance when I had them resurfaced. I guess this is why Mercedes does not resurface rotors when they do a break job. I was amazed at how worn they were at that mileage. Based on my experience I am suggesting you check the rotors for wear.