Builder delayed construction and cancel my flat booking

Dear sir I invested in 2013 Jan in Kalyan. Builder took 20% down payment, I arrange home loan from India bull for balance amount. From 13th till feb 2016 builder construct till 10th floor as got CC only till 12th floor against full 14th floor. Since then the work is stopped but in the mean time they called for some money and did my agreement for sale for which I paid stamp duty and service tax in Aug16. As per agreement builder agree to handover possession by dec16 + six month grace but till date and since one year there is no progress beyond 10th floor. Further the phase 1 investor approach media also for builders delay in jul-16. Now since builder got the CC for full building they started demanding money to pay in one week time. Upon non-payment they added interest on outstanding @ 18%. Still I keep asking the progress in work they sent me letter of cancellation of my booking. After one weak they called again and ask to pay 5 lakhs immediately and balance through loan. Which I said first sent me confirmation of reversal of interest amount. Which they refuse. I think builder intention are not clear. Their phase 1 10 building yet to deliver to investor who invested before 7 years. What if I pay my due till 10th floor and them don’t use money for same project and delay construction further. As per the new date of possession is Jun 2018. So almost 4 to 5 years delay from there end. Still can they cancel my booking and forfeit my amount I paid to them? Can I claim my stamp duty as refund as the builder cancel my booking?