Im not 100% on this but i thought dave was the boss of WM, thats the impression i got when i went there. He's a very well paid member of staff then as he's had a supra mk4 followed by a 355 so ive been told by m8's that also have been there and luckily walked away with similar opinions to my own.
I think at some point your going to have to go there with someone to help you keep a record of what is said, take a note of your statuary rights with you, tell him you want your money back and take it from there, then if they still play hard ball i'd get in touch with your solicitor give him all the facts and 1 decent letter from them should see you sorted.
I almost got stitched up by a main dealer once on a £48,000 car, it got sorted but it took 2 months, but i wasted too much time trying to sort it nicely and just kept being fobbed off with the, he's in a meeting phone calls. Until i got my solictor involved they just took the p**s, it took threats of court action, trading standards etc before they came clean.