Hi,

there are two cylinders: The master, and the slave cylinder. The first one is up at your pedal, the other one is down at the clutch. One of both could be broken - the symptom fits.

But as important as a new cylinder is the correct venting of the clutch afterwards. That may require your Audi dealer as he has the required venting machine. Manual venting often causes troubles!

Bastian

Das Buch zum Audi V8