my fronts began squealing at around 36k miles. Dealer replaced rotors, pads and sensors.

FYI, my idrive thing said i had another 15k miles before replacement.

ask your dealer to physically check the brake pads and rotors for tolerances.

i'm not so sure i would buy into the whole "cleaning thing" too many times.

if they are scrubbing your rotors to remove deposits, i would guess you have glazed the pads and they are trying to get new material transfer from the pads to the rotors.

do you spend a inordinate amount of time in stop and go traffic?

do you rest your left foot on the brake pedal while you drive?