What happens with the part ex value when they delay your order?
I would think they would have to honour it. I have just sold mine privately so I'm without a car for the next 5 months.
Dealer would have to take a massive hit on the part ex value after 10 months.
Always get a fixed p/x - hopefully the OP has done this. VW can compensate the dealer for delays which eat away at the P/X value, after 20 weeks from order acceptance by VW UK, I believe.
If the dealer cannot provide a coutesy car then VW UK should be able to provide one directly, again after 20 weeks from order acceptance.