Power of Residents Welfare Association to impose restrictions on alterations /additions to my house

I recently purchased an independent villa within a walled community. All of the villas within the walled community have the same front elevation. Considering my needs I decided to add another floor and make some alterations within the house. The sale agreement does not cite any restrictions and the agreement is the same as if it was purchased anywhere else. The RWA now says I cannot build an additional floor as it will change the front elevation with respect to other villas (main contention) and also there would be additional demand for electricity and water. My response to them is that since I have got the necessary building approval from the local municipal authority and as the land and building is my name I can make alterations as I deem fit. Furthermore use of electricity and water (common areas) depends on the number of members in a house and not on the number of rooms or size of the house. I even offered to install a water meter to ensure that no additional water is consumed by me My question is can such RWAs impose such restrictive byelaws and what are the remedies available to me