We both sign that register agreement then builder and his coustamar have not get any liggale right to use my flat without my permition because only I am the owner of that flat but his constant not ready to live coustady of my flat
and uses it on free of cost. But you have not mention what legal action taken against him in your answer please guide me for that .
If you want to lodge a criminal complaint against the builder stating that he sold the property but has not physically handed over possession and had been illegally keeping a tenant in the house, collecting rents from him etc, an act of cheating and breach of trust and offence as per IPC, the police may intervene and the builder would be made answerable to this by which the builder may put pressure on the occupant and make him vacate and handover vacant possession.
If the police do not want to intervene then you may approach a criminal court with a petition under section 156(3) cr.p.c. seeking direction to police to initiate proper legal action agaisnt the complaint pending before them.