a bet its a mk3
I am guessing from your past posts it is a mk3 8v, if it is slipping I doubt it will last, get them to check and confirm the crankshaft oil seal is all ok as it could be oil getting onto the clutch.
Lol, we had that problem in my mates car many years ago, tried to get to a party and on the way couldnt get up a big hill cause of it slipping. Gave it a few goes then had to give up and go home!