Vsa Warning Light On problems of the 2005 Chevrolet Suburban

Started engine, depressed break pedal to shift into reverse. Break pedal goes to floor with no pressure, break and stability warning light go on. I back up, then go into drive, travel about 50 feet, apply pressure on break pedal and again no pressure on pedal, Suburban slowly stops forward movement on level surface. I return Suburban to parking area and turn off engine, call service shop and make appointment for repair. Next week, 4/22 slowly drive Suburban 1 mile to repair facility for service. 4/23 repair manager calls to tell me that all the break lines are excessively rusted.