BPTP — Not handing over the flat inspite of paying 80% money of cost and again asked for vat to submit

Address:

New Delhi, Delhi, 110001

Booked flat in bptp park elite project taken loan from hdfc Bank given all money for which the demand is raised time to time which is approximately 80% of cost of flat.On checking about the possesion of the flat no proper reply received and yesterday received mail and message to submit VAT amount of Rs 19, 573/- by 24th November and delay in paying the same will result in penalty of 18% interest.
Absolutely absurd.No information shared about the construction or possesion just simply given the bank name RBL account no, IFC code and hauz khas branch.
Single earning member and put all my money and hope on this house with no hopes of getting the possession and harrsed by this time to time money demand from them, I am actually fed up.