brake pedal snaps down and makes a loud popping

Brake pedal worked fine until dealer installed software the changed parking brake from manual to automatic. Afterwards, the brake pedal began periodically snapping down and making a loud popping. Dealer has been unable to repair and is now telling me it is normal operation. Why have they tried to fix it before if it was normal, and why did it not do this until they did the new software for the parking brake? No answers yet.