I could be wrong but I think your more than likely the victim of what they call in the house buying market “gazumping” and the dealer had a private buyer willing to put money up front for your car that far exceeds anything the dealer would make on a Motability sell.
Agree ChrisK
I think more folk especially now are walking away right up to putting the PIN in. The reason I guess is because of dealer cock up’s, like this one. They have either found one in stock or a dealership is allowing them to dealer pre ordered vehicle with a qucker delivey time, or the vehicle isn’t the spec they ordered/have bits missing with no reduction in AP if they take it. Go back a 2-3yrs and it never happened to the extent as it is now.