Builder Logix Infrastructure ,Noida is issuing a Deemed Possession Certificate

The Builder Logix Infrastructure ,Noida has project named Blossoms County in noida who have offerd various categories of flats and are also registered with Rera. The agreement was done in year 2010 and due opossession was supposed to be in 2012. After a lot of delay they are offering Possession on Deemed Possession Certificate to its buyers instead of a valid possession certificate, as they have submitted the documents for possession (The documents submitted are incomplete along with the site) and have recieved an acknowledged by the Regulatory authority as recieved, and as per the Rera ruling if the authority does not respond to it with in a particular time of the submission of the documents, it would be treated as Deemed Possession and Builder can issue offer for possession letters to the buyers. However the works on site and the documents submitted and shown to us are both incomplete. Apart from this the builder has many dues and therefore he is not entitled to do any sublease for the offered flats, and therefore they would be undergoing an Agreement to SUB lease.. and they claim that the process is all legal.. would like to understand if the Deemed Possession can be challenged , and if the agreement to Sub lease beneficial if i have to resell the flat