Awkward! No magic fix but add pulling the seatbelt hard to the equation. It's going to take trying between forcing from inside, pushing closed from outside and pulling on seatbelts. A combination may just do it.
I have managed to open the door this morning. The clip was trapped in the area of the door catch. I removed the seal around the door frame & decided to slide the clip down the door frame with a piece of wood & hammer. I was then able to press against the door from the outside & release it.
“ Sigh of relief”
Regards to all.