Builder Cheated, not honoured the agreement and now, not responding to calls?

I booked a flat at Bangalore 2 yrs back, paid 50% amount as on date. As per agreement, builder agreed to subsequently hand over copies of property doents and BBMP approval plan. However the building construction is complete and he has not handed over any docs, always gave false urances and believed upon his urances. Now i came to know that he has not even taken BBMP approval. I have taken over the pocession of the building. i intimated him my intention to vacate the flat after he pays back my 50% amount paid with compensation. He is not responding to my e-mail, sms, phone calls. I do not want to continue with the property and builder is not responding. Pl advice.