Oc

Hi, In 2014 I had purchased a flat in Mumbai and the developer said the project will be ready by 2016 and the project was delayed now the construction is completed the developer is forcing all the buyers to take position and 90 % of the buyers have taken position without OC is it legally allowed . and most of them have rented their flats . when we are asking the builder for OC he is saying its under process now its more than 2 years we have not got the OC and the Buyers have made a housing cooperative society and registered it and have made a society and forcing us to pay the maintenance of the building is it legally allowed to do so . and what are the legal actions I can take towards builders please guide me in this matter . 1: Is it legally allowed to move in to flat or take position without OC ? 2: Is it legal to rent the flat without OC ? 3: What are the action taken by the government authorities if the position is taken without OC 4: Is it legal for buyers to form a society and charge maintenance 5: Who is responsible to pay all the property Tax and other amenites expenceis without OC