What to do in case of illegal construction and encroachments

I am the ground floor owner in the row housing society in Sec -51 Gurgaon. There has been an illegal construction done in my backyard by first floor owner of house. He has erected a lenter in the open area and extended it. This amounts to an illegal encroachment of my open area (10 ft outside my kitchen and 3 ft in the balcony). The construction is causing me lot of inconvenience and blocks my sunlight and open air. The process of erecting the structure even caused harm to my existing walls, which I just got painted, that also made me suffer monetary loss. Needless to say, this expanded structure is not permitted as per the original builder plan. I have raised it with the first floor owner on number of occasions, but he didn't halt or demolish this construction. I raised this to RWA, but of no avail. Please advise what should be my legal and official resort in this case. I can lodge a complaint to MCG, but I hear they don't take swift actions. Please advise.