Society handover and selling of stilt parking space

Builder has taken 25000 from every flat owner in cash and transfer for society formation while OC was obtained 4 years ago. He took money in nov 2019 and is giving lame reasons of covid. He has not paid water bills for a year and even watchman salary over 4 months inspite of us paying regular maintenance. It’s a small apartment with 20 flats in Navi Mumbai. He has also sold one large stilt parking to a shop owner who has also covered the area with bricks and put a shutter. This area is common area and cannot be sold. The person who has bought has also rented out the place. How do we deal with this builder 1) to get him handover the society as he has been postponing it for over 1 1/2 years. 2) we have paid the water bills to the tune of 75000 as we didn’t want water connection to be disconnected. And also paid security. We want to recover this amount. 3) how do we take over the common area from the person to whom builder has sold parking space. Which is not at all marked as shop in the plan.