@tinytim if part of the Motability package is home delivery (which I don’t know if it is or isn’t) then if a dealership refuses this service, the customer should contact Motability who will organise delivery, be it forcing the dealership to honour this, or by other means as it’s part of the package you’ve paid for.
If it’s not part of the Motability package, then being disabled doesn’t make a difference. You would hope that a dealership who didn’t usually deliver to home would make the extra effort based on the disability, but there under no obligation.
I have internet purchases delivered and need this service more than abled bodied people, but I don’t get free delivery based on my disabilities.