you can take following legal steps
1 if you are in a housing society first you should write complaint to the society , it is society's absolute responsibility to take action against the owners who make other residence life miserable ,it is public nuisance.
2.Make a police complaint, do not have to produce any evidence let police call them and investigate.
3. Send them a legal notice through a lawyer for causing you trouble and send the same to society management
The act what they do will come under public nuisance, so police should take a complaint.
if police do not take any action , you need to approach a criminal court with th a private complaint.
You can also approach deputy registrar of your area and file a complaint.
all the steps you can do it yourself except sending them a legal notice,
You should take this strongly before the society administration.if every family in the building start troubling each other and challenge others for evidence or proof , what will be the situation, so society administration has the authority to take action and warn/fine the flat owner for this deliberate torture.