Yes it can be fixed. Depending how far gone it is the costs are about £20 or about £150 for parts. I repaired one before Christmas.
https://www.a2oc.net/community/index.php?threads/gear-change-issues-2003-tdi-150k-miles.34450/
Yes I did it myself. The part needed depends on how far gone the tower is. A bush and a seal may be all it requires, about £20. However it could be a mess and then you need a new Tower (or a good used one). Your gearbox may have water in it so you would then need a couple of litres of gear oil. The job is easy by A2 standards.
If you change the tower yes you change the VW thing. If you change the seals you keep the old one.
Thank you, but A2 days going really badly at the moment. Car getting close to the thrashing with a branch treatment.