Builder not returning back booking amount

I had paid Rs.33,000,00/- (Thirty three lacs) to a reputed builder having their H.O. at Naupada,Thane (W) towards booking of a flat in their project at Naupda,Thane (W) itself in the month of April 2019. Total cost of the flat is 2, 30, 000, 00/- (Two crores & thirty lacs). It was decided to pay 33, 00,000/- towards the booking which I had paid as stated above and rest of the amount will be paid out of selling out my flat in Goa latest by July 31,2019 failing which deal would be cancelled. A MOU thereof between me and the builder was signed accordingly. Unfortunately I could not sell my flat in Goa within said period. I informed builder accordingly vide my email that I could not sell my flat in Goa within stipulated period and requested them to return back my booking amount i.e. 33,00,000/- asap as I was in urgent need of money for my urgent family reasons. Regret, despite sending repeated mails, WhatsApp msgs and several telephonic calls, builder is neither responding my calls.