Possession Delay and increase in super area

Hi, I entered into booking of 2bhk + store of 1080 sqft super area with developer in may 2015 and paid the booking amount in dec 15 we entered into agreement for possession within 36 months. I paid all demands on regular basis while paying demand in 2019. I come to know the bank has decreased my sanctioned amount as value/ status of property has entered into caution list of bank. I arranged funds on own and paid the dues. I got the receipts for same stating 3BHK property 1080 sqft. on visiting site I found the dewelled unit is 3BHK and on basis of received receiept I was sure it is 1080 sq ft area with architectural changes only Recently I got a demand letter for final 5% amount to be paid at time of completion. along with additional demand for 246 units stating units size has been increase to 1326 sq ft. Verifying from UPRERA site I come to know the estimated completion date as per UPRERA records is jan 2019. I dont have any additional funds to pay for this unit. also there is no hope of loan enhancement from banks. Please suggest, I dont want to loose this property and also not in position to pay the amount demanded by builder. Please suggest Regards