As Gene Hunt said, try speaking directly to VW head office.
I found rust on both of my front arches. The dealer said VW would not cover it under warranty, and that no good will would be paid. I rang VW myself, and after a 24 hour wait they said rang back and said they would pay 70% of the bill. A little more moaning and we settled on VW paying 90% (80% by VW head office and 10% by the dealership)
It pays to moan a little mate.
Hope it gets sorted for you.