Unregistered Association

Hi all, i have purchased a used flat of 750 sqft last year in chennai. Till me purchasing it the maintenance was handled by the builder. After that the person who gave the property as JV had called himself as a Association president and taken over the maintenance activity. Till date they have not registered this association. The person from whom we purchased the flat is a relative to that Association president who has another 4 flats with him other than the one which was sold out to me. This person is not paying maintenance to these guys because of their internal family issues. In last November i found that the assocation people are collecting a huge money as maintenance and they are not servicing properly. Hence i started raising questions against them in their whatsapp group. Suddenly i was taken out from that group and i received a message from the Secretary that they are not willing to look maintenance activity for our block and asked me to stop sending money to their individual account. I have vacated my tenant and the flat is vacant for last 4 months. Please suggest me how do i resolve this issue. Thanks in advance