Delay in possession of property by builder. What to do?

Based on false commitment from builder we paid in full by May 2016. As per agreement possession was due by Oct 31, 2016, which is till date not done. Now builder is demanding additional money in the name of advance maintenance, in spite of no electricity, no meter, no water tank, no gym, no parking, no other amenities as was promised. Now if we issue legal notice, he has threatened us to play more foul and delay possession further. He is denying compensation as mentioned in agreement by taking shelter of force majeure, even though nothing as such happened in Bengaluru since over a decade. He has extorted money from 2-3 families, who paid the same, driven by sheer situation to complete wood work and move in to the home and thereby save on huge rent expenses. No association of owners has been formed, and yet he is continuing the extortion and without the same he threatened not to allow us to do the furnishing, nor to allow temporary electric connection and water facility.