Dannyboyr32 - very good point.
Don't let them fob you off with a repair. Contacting VW is good, as is written letters. Unless you come out of this *smiling* with a really good deal, then it's really worth just walking away with your cash, put up with the pain of ordering new, and look forward to finally getting what you almost, almost had!
They've opened up the ED30 orders it says on another thread, so there should be no problem in the long run, but whatever you do, when you're spending so much money there's absolutely no reason why you should share the pain of their stupidity.
How can someone who works in a car depot not blooming well reverse a car without trashing it? 
Yes put it in writing whatever they say because come 6 months time when you're in a court or wherever arguing the whys and wherefores the truth will get distorted.....
Put a letter a head it WITHOUT PREJUDICE and ask them to reply in writing........send a copy to the principal and a copy to VW........the franchise doesn't like getting in trouble from VW because they may have the power to make their life very difficult.......
This is a serious issue and they are expecting you to drive off with the same car, if I were you, I would push for a new car and a very good replacement until that arrives. Not that I would tell you what to do but I know how emotional it can be when you've saved hard, set your mind on something and some twit with a pimple and a $hit sales patter tries to ruin it for you....................remember you are the CONSUMER..........
Also quoting Trading Standards and Sale of Good Act (just take the relevant paragraphs) scares the life out of most people selling sub standard products..............