As in? – Ask them to prove that it was a mistake. (I don’t believe it was).
Have they re-ordered your chosen vehicle with them – assuming it is still on the scheme (or even still in production)? – No but the guy is apparently trying to re-find me another new car.
If so, and there has been a change of AP since initial order – has this been ‘discussed’? – What is AP?
Have they offered anything for their customer service faux pas? – Not yet
You are of course free to go wherever to re-order a new vehicle but could end up at the back of the queue. – Aren’t I at the back of the queue anyway, now?
Have you spoken with Motability? – Yes, they’re just saying raise a complaint with the dealer.