Builder asking more money before possession in name of society

Dear Lawyer, We bought a 1 bhk flat in reconstruction project in Bhandup in Mumbai. Builder delayed the project by approximately 6 year (promised in Dec 2012, but still no possession). He is giving excuse of changed policy from government. He did get all the cc in 2014 I believe, but even after that he didn't complete the project in time. However now project is complete but he is asking more money (approx 1.5 Lacks) in the name of society. Since this is the redevelopment project, existing society was already there. Now in his demand letter he sent extra 1.5 Lacks demand, and asking us to pay directly to society. He is saying he has agreement with society and we are bound to pay that money, otherwise he will not give the possession. I told him that I bought flat from you, not from society, but he is not listening and not giving possession. 2nd thing is, he is asking to pay 1 Lack for parking. He is saying as per RERA he can sell the parking. Earlier we thought that he will give parking free, as I believe builder has to give open parking free, but he is saying will not give parking if you will not pay. One of my friend got agree and he paid 1 Lakh extra and he put parking clause in his agreement. 3rd thing, he has changed the structure of flat and changed the direction of main door to south (from east) against our vastu, and he never informed us. When I visited site, I complaint for same and said we need door as per earlier plan, but he didn't do anything for that. Also, due to restructure he is saying area of flat is increased and asking more money to pay for that increased area. In fact the flat looks very bad after his restructuring, he added extra passage in the leaving room which is absolutely of no use and now leaving area become too small, but he is asking more money for that increased area and also asking for supplementary agreement, with all our expenses. During complaint he said he will swap the flat with some other owner, but it was all false promise and it never happened. I also asked him some changes due to small problems, which he never did. I have all these mail communication with builder from Jan onward, but he is not ready to give possession unless money is paid. Please advice me what to do. Its been already delayed by 5-6 years and builder is not listening anything, he just need money. Is he authorize to ask us to pay any money to society? We are not even member of society withou possession. Also for parking, isn't he suppose to give open parking to us free of cost? Please advice me on this. Thanks Rakesh