As FOD isn't officially available in the UK you might struggle to get them to pay for it, might not be the thing to do as an official dealer. And you've done well to get that sort of 'agreement' anyway, I'm surprised they don't just refer you to the paragraph that's always there, referring to their right to alter the spec at any time and correct at time of printing etc etc. Page 6.
I’ll pay myself and get them to refund it, sure it’ll be fine I’ve got it in writing and have had since a couple of weeks after i took delivery of the car.
That’s all good and well, they could have referred me to that paragraph, I could then refer them to my right to return the car within a set period, works both ways fella.