I've had this issue for a few years now. It first started off with the brakes making a "water gushing" noise when I brake down at slower speeds. I've had it fixed before, but it always returns. Now, the sound is more of a grinding noise. I admit the car was bought in 2007, but I have had to fix this problem often, though this is the first time the noise has progressed from it's initial noise to the grinding noise.