Golf auto transmission

Before replacing the transmission I would have returned to the dealer armed with the information from your mechanic and asked them to check it themselves to confirm that the auto is shot as you have been told. It does seem to be too soon for auto trans troubles to set in. If the dealer confirmed that the auto does need replacing you would have some ammunition to approach VW with, but without that you don't have much of a claim. I am also guessing that the car has done 120,000 km or so, which would reduce any claim you might make further. I would doubt that you would get far with VW on this.