Open reserved parking issue

When i bought my flat in Pune in Dec 2017 through promoter and broker. These people and builder's focal person mentioned that the flat comes with open reserved parking. After buying flat builder mentioned that they will allocate open reserved parking shortly. Even after doing several follow-ups, they mentioned the same things. Now builder wants to form society so does those people who have bought flats in 2016. When we raised our parking issues, he said he will not provide open reserved parking instead it will be open parking for all. This is because builder mentioned that there are 60 parking space (open + close) in RERA for 65 flats. When checked we saw actual marked parking slots are less than 60 ( open + close), but builder have land for new building in our compound. We got to know from the builder that if we pay money then we can get open reserved parking even closed also (while booking they mentioned that there are no vacant closed parking). 1. As per RERA, Builder cannot sell open reserved parking. So builder breaking their promise and asking money for open reserved parking is valid? 2. Can we file complaint against builder? If yes, then what documents we need? 3. What legal steps we can take to resolve this issue? 4. Any easy and valid solution?