MCD refused to take action against Unauthorised Construction & Commercial Misuse of Residential unit

Owners of some units in our residential building are operating full-scale offices with 30-40 people staff members in each such office. They've illegally covered the set backs and shaft areas of the building and also started office in the basement of our building, the area of which is not counted towards FAR. The other residents of the building and RWA members complained regarding such misuse and unauthorised construction to MCD, but the MCD officials threatened the other residents of the building orally upon their inspection visit that because no one has completion and occupancy certificate, they’ll demolish the houses first, if we complain regarding the commercial units. Some brave residents still filed complaint through CPGRAMS and DDA STF Portal regarding the aforementioned issues but they too just received the standard reply that the property is situated on Notified Commercial Street, hence no action is pending to be taken by MCD. The property abuts a notified commercial street but does not qualify as mixed use property, and it was clearly and expressly stated in the complaint while citing relevant provisions of the MPD 2021, chapter-15. Yet, the MCD refuses to take any action. In the same way they have replied to our complaint against unauthorised construction that the property is old and occupied and since no construction material or ongoing construction is seen on the property, no action is pending from their side. What action can we take against this & against MCD? Is there any law or notification that prohibits MCD from taking action against such illegalities if they are old and ongoing? Please help