About property

I have gone to see a flat, the flat was with terrace on the second floor, the terrace which I have bought with this flat was divided in two flats, Flat no. 2C and 2D. When I was finalizing the above flat no. 2C I told promoter that. I want whole terrace and you have to give me permission to make pergola on this terrace for my safety and privacy, than, I will buy this flat with terrace. They have agreed and have told me that they have to give a very very small portion of the terrace to flat 2D for his ventilation, but I have made a condition that you have to give 10ft. Partition Wall between the terrace of both the flats for my privacy and safety, and they were agreed for this also. They have confirmed me through mail and given me the plan also. After their confirmation, than I have bought this flat 2C with terrace. I have made the full payment in February 2019 and they suppose to handover the flat on 28th February 2019 but they postponed it and handover to me on 12th May 2019. At the time of handover I asked them that the wall is 6fts they suppose to give 10fts but they said they will give 4ft louvers above that wall and that is still incomplete. Than after I started my flat and pergola work on the terrace, after a month or so, instead of giving louvers on that wall, they asked me to break the Partition Wall. I said why I should break this partition wall, this was a deal with you, they said flat 2D is making problem for this and they have complain it to Municipal Corporation, I said this is not my concern and I have paid you for this and this is your duty to regularise the plan. After that I requested them if you have problem I am ready to leave this flat, please take your flat back and return my flat money and the money which I have invested in this flat to make it, all with interest @ 24% per annum. But they didn’t replied. After that we had a hearing at Municipal Corporation, there I have shown them all the plans mailed by promoter, but Municipal Corporation told me that promoter has not sanctioned the plan and cheated you, so they have to demolished it. Sir what steps I can take against Promoter and what can I do to stop Municipal Corporation to demolished it.