Ownership Flat In Pagdi Building

My family is residing in this building since last 50 years. 35 years back we purchased another flat in the same building. the landlord sold us that flat on ownership basis with agreement stamp duty and registration paid. now the landlord sold the building to some investor who is not really interested in re-developing the building. I want to sell my ownership flat to someone. but the new landlord is demanding 33% as transfer fees. he says that the flat is not considered ownership as the building is pagdi. please guide.