I want to get Money recovery from builder. I am victim. Help me

Dear Sir, I live in thane west. 4 Years back I booked a property with a renowned builder in Kolshet Road Thane and given required booking amount. Since I had very good relationship with builder and he asked so I invested 50 lacs on 12% / year interest rate. I thought anyways he is building the house and I have also booked one so as the work progress I can keep giving him money out of this investment against my booked house. Initial 2 to 3yrs were very smooth as I was timely gettinf my interest cheques. On the other side the property I booked never progressed and its still same as it was 4 years back so I withdrawn my booking amount somehow in last 1.5 yrs. Now I am really facing difficulty for recoving my 50 lacs...and in last 5 months I have not even received my interest cheques. Whenever I talk to him he give promises but never fulfill. I am really tired and frustrated now... Can someone please help me... I really need your expert advice to get out of this difficult situation..