a new clutch and dual mass fly wheel was fitted to my work van at a cost of £960...got it back today but didn't even make it home (20 miles), the clutch pedal has went right to the floor and has stayed there. its selecting gear when engines off but not when engines running as the clutch pedal is stuck in the fully depressed position. its going back to the garage tomorrow but whats a likely cause? what have they done wrong?