1. A "unregistered" entity (Society /Association /Club) is legally an null & void and has no jurisdiction to collect any maintenance whatsoever, nor disconnect water /electricity or whatever.... in any way. Such Acts are criminally prosecutable offences (Intimidation, Harassment, Misrepresentation, Cheating etc....), BESIDES being offences under the Income Tax Act.
2. You can file a Police FIR, requesting investigation and charge-sheet, for offences like cheating, intimidation, fraud etc...., against the person, supported with all relevant supporting documents.
3. IF the Police does not take action, THEN you can file private criminal case u/s 156(3) Cr.P.C., in the local Magistrates court, seeking directions to the Police to investigate and file charge sheet.