What to do in this matter ?

I have my own business in an area . i am doing the business in that area since 25 years, its a rented premises and i used to get the rent bill, now few years back the owner of the land died and since no one was taking the rent i started giving the rent to rent control someone had purchased the land but he has not given me any proof that he is the new owner of that land. after 6 years he is now demanding us to increase the rent and enter into an agreement of 11 months ,according to my trade license i have a working area of 600 sq ft but my premises is of total 2500 sq ft where no trade practices takes place its just a storage place . now the new owner with the help of a local goon trying to haras my labour and trying to create a terror among my labour . the local goon demanding money and the new owner is claiming that i am a subtenant of that land and we are there illegally since 25 years . the owner is not giving us any proof and further he is stating that the rent which we are submitting in rent control is also illegal. I have legal documents like electricity bill which i am paying since 25 years i have my trade license , pollution license, gst registration, rent bill , rent control submission bills please suggest me of what to do in the matter