Hi, I have a similar problem on my 2002 gti with rust on the front wheel arch. Took it to VW and they said that it was a design fault with the car and they wouldn't be doing anything about it. Have a few friends that are lawyers who are going to have a look into it. The quote from the garage was £980 to repair it which they can shove up their ar$e. Have a guy up north who will replace and spray it for £250. Going to see if its worth taking the legal route first. Not my fault there was a design issue with the soundproofing rubbing on the wing.