My daughter has just bought a T reg 973cc Corsa GLS. It's a nice clean little car with only 43,000 on the clock. The only problem it has, is when braking at speeds over 35 - 40 mph, the brake pedal goes up and down, very rhythmically and the braking is affected with what feels like brake fade then ok then fade then ok. Can anyone suggest what to look for and a possible solution? Thanks in anticipation