Unregistered apartment association

Sir, We have a flat in a group of 40 apartments. We are facing a peculiar problem where some flat owners have declared themselves as custodian of the apartments and formed an association even when there is a registered association. These people have not registered their assisted and has started the running of the apartments. Later they formed an AD HOC committee and started running the association. Some members are paying the maintenance to the old association and some to the second unregistered body. Now the ex president of the second body who has constituted the AD HOC committee has been laying of pipelines and water meters from his own pocket and has been threatening the members to pay him for the expenses incurred by him or else he will stop the supply of water. Those who paid the maintenance to the old association were considered as defaulters by him and taking a clause in the original by-laws where there was a clause stating that any defaulters of maintenance would be given seven days notice and after which the supply of water will be stopped. Now my question is whether the AD HOC committee formed by the unregistered association has any authority to do so. Water being an essential part can it be arbitrary withheld. That to by an unauthorized person or body. Please advise.