Same issue here, they replaced the rear pads and sensors but haven't had a chance to drive the car enough to see it it is fixed. I think they actually installed the wrong pads on the rear of the car. There's film of rust on the rotors from them washing the car after service and the pads have only worn away about the outermost inch of the rotor - looks like the rest of the rotor has not even been touched by anything. Wondering if they put 328 pads on?
2008 335xi Sedan - Monaco Blue/Biege Leather, Steptronic, Premium & Sport pkgs