Chevrolet Kalos

Had my Kalos 6 months, 2006 1400 4 door. Had to have corrosion removed from the front discs just after I collected it, as I returned it back to the garage due to front breaking problems.
Since then its been back twice and had two sets of discs n pads put on, due to a faulty batch, acording to the garage.
Now it doing it again, the garage have offered to have it back, but told me they think im breaking excessivley....?
It is only when breaking and feels like the discs are warped, a bouncing feeling on the break pedal, Not as hard as an ABS activation though. There is a noise to match when the car is almost at a stop, a sort of repetative 'werring' noise.