Developer Refusal To Honor Content Of Register Document

Developer has refused to give me any finishings as per annexure 7 of registered document,stating that the signed application form it was mentioned as bareshell unit which was month and half before registration after which terms were renegotiated,1) as my 90% payment is gone can a developer bully me into signing a rectification deed and take possession of a bareshell flat.2) can he take my final installment and not give possession until i relinquish my right of claim of furnishing as per agreement.3) as the registered document supercedes all earlier unoffical understanding can he use those against my calim