I have owned my car since last September and on a few occasions i have thought my brakes weren't working as they should. Basically i have been approaching a roundabout for example, pressed the brake pedal, and i slow down, but not at the rate i should. The pedal feels firm but doesn't respond anymore no matter what pressure i apply. This has happened half a dozen times in all. At first i thought it was my fault, catching the throttle pedal with the outside of my shoe but now i'm not so sure. Are they any known braking problems? Car is a 2008 1.9Tdi Sline Avant. Thanks Nik.