That's totally crazy, it should not matter where you purchase your VW from.
If a vehicle requires some warranty work to be carried out, any VW main dealer should be able to carry it out.
My previous car was purchased in Stoke on Trent, but i took the car to Chester to have it serviced.
The silly turbo boost gauge on the dashboard, gave an intermittent reading, whereby the boost needle worked sometimes, then for a week or two, it didn't move.
Fiat had a software update for the car, which required the removal of the gauge, and a lengthy download of new software.
All in all, my car was in the Chester workshop for nearly four hours, and as it was in warranty claim, it did not cost me anything.
Out of warranty, it would have been a £346 bill.
The software cured the problem.
Never did they say, take the car back to where you bought it from.