The statement reads to me (and I am not judging you so please dont take offence) you spoke to this dealer and explained your issues, they decided to help you out and do something they should have not without the ok from motability and that is deliver the car to you and have you enter the pin at home. It was forgot as in your state, you were probably happy to have a person to talk to that you felt comfortable with. So for some reason during this they and you forgot to do the pin, the next day the boo boo was noticed and not unreasonably they asked you to return the car if you could not come in and do the pin as if they would travel to you again for this they would be a loss and down on money.
I wonder did you then call motability to have a complain, which in turn put the dealer who had try to help you out in a lot of trouble with motability for not following the correct procedure, what you should of done is ask the dealer how to fix the situation, your first question when they said you needed to come back in the car should of been, can I come and sit outside in the car and enter pin on the tablet why I am sitting outside…
Again I may be wrong, but I am presuming this might be the case
@oscarmax please be careful with your wording here, just because someone has panic attacks and fills anxious and does not want to leave their home, does not mean they are not fit to drive, I know I dont like going out much, I dont do public transport because of ptsd, but I still drive, infact the car is my second home, I am very comfortable in it!… and thats not even my disability the ptsd, although it could be easily.