Karrm Infrastructure — I have bought 1 flat in 2015 still waiting for possession

I have booked one flat with Karma infrastructure pvt ltd. At sahapur in 17/08/2015 as per promise they suppose to handover this flat in 3 yrs. That is in 2018 but they not fulfill them self promise. All work has stop saying that they don't have workers..or any response from karma infrastructure. Till time a have paid 516000 rupees for flat. even i have done registration also Please tell me when i will get the key for house ... i have visited your head office thrice also the staff keep changing every time and they don't have answer too...