You can always try quoting the Sale of Goods Act 1979 at them: The Goods don't match their description.Thanks for the responses. I am indeed in UK, where the game is listed as being Vita-compatible:
https://store.playstation.com/#!/en...-psp/cid=EP0006-ULES00025_00-GPCNEEDFOR000001
The fact that all the e-mails I've gotten in response have said "but the game does work on Vita!" kinda back this up as well.
I'm gonna wait until Monday to see if I get a response from this latest e-mail, and if not I'll give them another call and just try to be a lot more firm about getting a refund I think. I guess trying to emphasise the fact that it's not working as described and that's what sold me on the game.
And once that's sorted, I've got my second uphill struggle with ThrillVille: Off the Rails, a game which I bought of UK PSN which is completely in French...
I guess the fact the goods were misrepresented (and are still being misrepresented) means you could try mentioning the Misrepresentation Act 1967 too but that's an unwieldy instrument and I don't know how you'd actually go about leveraging it.