Whether they have broken their contract depends on when they told you the delivery estimate. If it was before you signed and you signed on the basis that you were expecting delivery within the time given, then it might be a misrepresentation (false statement of fact that induces you to enter into the contract).
The problem is that it's only an estimate, so is liable to some slippage (but not as much as you're seeing). IANAL, but I don't think there is a breach of contract here. The only thing you can do is lean on your dealer and/or VW UK and try and wheedle something out of them - compensation, freebies, etc.
I wouldn't phone them. I would go in and talk to the sales manager face to face. Take a printout of the email with you so you can wave it in their face.
That's a very bad message (generally, and from a spelling/grammar/punctuation point of view). Is the huge blue font from the original? He apologizes for being late in getting back to you but doesn't say sorry for the order being messed up or provide any reason why it happened in the first place. He also says he heard "before" he went off. How long before? The same day? A week? If it's anything other than the last day he was in, then it's pretty poor on his part.
Re-ordering puts you to the back of the queue. My Mark 6 order was placed in mid-March, a couple of weeks after I visited the dealer. Delivery was slated for July. It went missing in June. The dealership re-ordered the car around that time and I finally took delivery at the end of October. My total wait was twice the original estimate. When they re-order it's as if you'd gone into the dealer on that day and placed the order yourself. They just do it without you being there.