"Rear brake caliper replacement"

"The car's brake pedal becomes very hard if a ABS brake is made (For a orange robot light or other car that swings in front of you) and the idling is the irregular. Audi dealership have replaced all possible air pipes that regulates the whole cars air intake and outlets. Their next solution is to replace the brake booster pump. But want a second opinion. "

"Rear brakes only"