When i had my old one this was the clutch pedal switch! Search for it, it's a sensor on the end of a plastic screw ( great design! ) The thread gets stripped and it falls out of it's metal housing, now i used a few cable ties to keep it in place, well 6 in fact! Then i bought a new one from Seat which was around £8 i think!
Could be other things but as i say, in my old one it was this, it's worth a check.