Cctv installation without permission

Hi Sir, I`m Shyam prasad from Hyderabad living in a 4 storey building with 2 flats on each floor. We stay in double bedroom and a single bedroom flat is beside our flat. The lady in side flat had been creating nuisance from last 2 years claiming that we abuse her, pass comments on her, peak her house and disturb us regularly and abuses our whole family. On top this she complained to police twice and we had to counter it another complaint. CI spoke to both parties in police station and compromised both to not to have such issues and gave warning to her. Fact is, their flat is enclosed in grills and main door is 3 meters from the grill entrance which proves there's no chance to peak into their house. And we never passed any comments on her. A week ago they installed a cctv on their external grill focussing towards our flat and stairs without informing us. This is so annoying, she started nuisance and she's never ending it and now it's threat for our respect. People started asking why the camera is pointing towards your main door. We spoke to police and they are in support with them, saying that its good for your safety ? Why are you bothered if you aren't doing any mistake ? They have installed on their grill we can't enforce them to remove. Please help me with what legal actions can be taken again this issue. We can't compromise on our privacy and can't tolerate this nuisance with abusive language.