If you placed the order in November for a factory order, that’s at least four months from November, adding a short delay for Christmas and new year and that’s the end of March. You could ask your dealer and Motability if they’re willing to hold onto the car for as long as possible. This would buy you some time, might not be much though.
I’d just ring Motability and have the conversation and see what they can do. They’re good at problem solving too.