@tinytim have you written a letter to the dealership and asked them for a reason why they are not willing to deliver the car.
If I’m honest I would walk away and go to a dealer that is willing to do this and get it in black and white on the order form.
If you find no other dealership is willing to do this and put it in black and white on the order form. It would be more difficult to prove discrimination, unless you have concrete evidence a retail customer as received better treatment.
Its also worth remember salesmen are the worse for telling porky’s promising the world and then going back on a verbal agreement. Thats why it is important to get it in black and white on paper at the point of ordering.