When VW "lost" my order for my GTD, I was getting nowhere, so I ended up writing letters to the dealer principal, the sales manager, the company secretary for the chain of dealerships and someone high up at VW UK whose name escapes me. That finally got things moving and because they'd messed up so badly, I ended up getting the three year servicing deal for free, plus some other odds and ends from the accessories catalogue like rubber mats. My experience showed pretty early on that the customer service side of VW UK are utterly clueless - it took weeks for them to find out what happened to my order. I was ringing up time and time again and they kept telling me they had no idea what has happening to it.
If the car isn't as ordered and the specification states that it has anthracite wheels, then it's a breach of contract (goods not as described) and you're entitled to reject or get compensation. They should at least make some sort of gesture of goodwill.
If Golf7's company does a lot of business with VW.de and VW UK, then surely that's an incentive for them to get their fingers out and sort out the problem? I'd be using that as an angle to get things sorted out.