Dream Shine — complaint about non completion of project since 2013

I have booked flats in 2013 with dream nirman project - nalasopara west possession about to get in dec 2015 till now sep 2019 no news when we call builder the office people said he is outside builder escaping to meet every time, no proper answer from office staff, no positive news on the handing over the flats, i have paid him 90% of the total flat amount. Builder has constructed the building b & c wings are ready and already given possession to customer but "a" wing works stop. Also bank has put the notice outside this wing. Kindly need advise how i can get legal advise to get my right.