Invalid GST Registration ?

Pia Saxena (CA Final Student) (83 Points)

05 July 2021  
I rented out a shop to someone and he left the place and gave it to some one else without my knowledge. There is no paperwork done with new party and me. He took GST regs of my shop where he is running his buss now. Is it valid or I can take any action against him as there is no legal rental agreement between the new party and me ??
Please guide.