Nothing too serious I hope
Clicking could well be a stripped gear in the motor. There are plastic pulleys in the cable mechanism which moves the glass but that tends to make a crunchy noise when they disintegrate and the window moves a bit then gets stuck.
Most D2 parts became obsolete at 15 years old. Almost all the remaining stock went to Audi Tradition so its now very difficult to get hold of any original parts in the UK.