Natis document frustration

I bought a car in June 2020 and they received the natis documents from my written off car which they had settled. Now I can't remove that written off car from my name since they have sold it and seemingly lost the natis documents. I can't renew the disks for my two other cars as I need the natis document to deregister the one that was written off first. It has been a frustrating 2 years as I'm stuck with expired disks. MFC can't assist as the dealership settled the car and not me. I have tried everything and I just don't know what to do anymore. I would never recommend this dealership to anyone because dealing with them is a nightmare.......