Sale deed & rtc issue

The seller cannot claim ownership of the land he alienated. 

Your rights cannot be extinguished as you have obtained a perm injunction,

See if you have any land grabbing acts in your state. You can lodge a police complaint under such acts. All other criminal proceedings also can be initiated against the seller, All buyers must unite to fight such unethical practices.

First off all you complete the revenue records. Take Inedx 2 along with application form and wardi notice to the revenue ofiicer and get your name enterde in ROR.

You may first apply for mutation of revenue records on your name on the basis of registered sale deed. If the threats persists you may file a civil suit seeking mandatory injunction against the builder from interfering with your peaceful possession and enjoyment of the property.