@Robert.
You first to asked about this on July 10.
Many of us on here including me advised you to phone around other dealers for stock cars, or cancel the order and start again.
Obviously you decided not to take this advice and are in the same position, and another month has passed.
Only you can decide if you’re happy to wait for the car you’ve ordered to finally arrive or whether you should call their bluff, cancel the order and pay another £700 AP and re-order.
But it sounds as if you need to get a bit more demanding and authoritative in your dealings. Have you escalated your concerns to the dealer principal or Motability?
Good luck and please let us know how you get on.