Harassment of elderly citizens

Hi, Need legal advice for my parents who are in 60's and 70's respectively. My parents live alone in an apartment in South Kolkata. My father had a surgery 3 years back which had quite financial burden on them. At the same time, the other residents of the apartment wanted external coloring and my parents were being forced to pay for the coloring costs. My parents expressed inability as well as requested to postpone the coloring as my father had just been discharged from hospital. My parents have sugar and BP. The residents went ahead with the coloring amidst my parents discomfiture. Also they have blocked access to the terrace by keeping the keys with them. My parents paid regular maintenance costs and the receipts were never handed to them. My parents are not being allowed to use passage light. Today i.e on 12th July 2016, the caretaker had given veil threat to my parents that even the individual water connection will be disconnected. My parents are under tremendous mental pressure. We both brothers live in North India. Need legal advice on this. Regards, Sandeep