Ways to disturb peace

Hi experts We own a property and as per my grandmothers will my father has ground floor, my father's younger brother is given with the first floor and my father's younger sister is given with the second floor. Now everyday my father's younger brother his wife & their son are trying to harrase us in different manner. They are throwing waste from first floor to ground floor and cutting our telephone wire and cable wires. We gave multiple written complaints to police against them but no action is taken. We doubt that they have some approach and hence whenever we give a complaint no action is taken over it. Even my bhua is not residing in this house and they have open her portion too. I am living in different state & i am always worried about my parents as these people are not afraid of police or law. The police has filed kalandar case over us and still if we tell that we are facing these issue there also no action is taken. I am really fed-up with their behaviour from last 2 years and now i need some metal peace. This is the reason because of which I can't enter my own house as they are keeping eye over us all the time and trying to put some false cases over us so i lose my job. Pleae guide me whom should i approach now so that these people have some fear of law & they start behaving and let us live in peace.