Right to Privacy

Back ground: We are a family of four. Have been peacefully living in rentals since three decades across the country. We are residing in an apartment with four flats on a floor. The people living opposite bought the house nearly a year ago. They are a young couple. About three months ago, they engaged in a verbal fight with thus against no backdrop of issue. The issue was flagged to the society manager and neighbours resulting in them getting a warning. Current : our society is guarded by cctvs including in the lift. The individual floors donot have cctv. I assume it is to retain the privacy on the floor. Two days ago, they installed a cctv camera outside their house. We feel its an invasion to the privacy since the society security is being well taken care of the existing cameras. The kitchen windows face each other and they installed another camera right on the beam facing just our window. We are highly appalled by such uncivilised behaviour coming from them. How do we go forward with this?