It helps a LOT going to a dealer where they know your face. Luckily the 2 dealers I use are sick of the sight of me
Another piece of advice I can offer is don't go in there with a bullish "I know my rights" attitude off the bat. Give them a chance with the softly softly approach first, you've just bought the car you've always wanted, you're gutted the wings are rusting, what can they do for you..... that kind of peace keeping bum licking shat. From talking to friends I have at dealers, warranty claims are an absolute paper chain and bureaucracy nightmare for franchises. VW HQ are difficult to deal with for them, let alone us. So will naturally try and shy away from it initially. Go there on a Friday as well because moods are generally better because of the impending weekend.
Not making excuses for them, but a little bit of friendliness goes a long way. If they fail to deliver, THEN you can unleash your wrath
I was extremely fortunate in that mine only needed one wing and they did it within 2 days of my complaint and to an amazing standard. You would never know it had a new wing, not even under street lights at night.