Extortion by apartment association office bearers

Hello Experts,

I am staying at registered society in Bengalore. Society is registered at registrar office. I am religiously paying maintenance charges. Recently our EC(executive committee) proposed(In May 19) for Kaveri river water pipe line connection for society for which they provided estimated cost of approx 66000/- per 1105 sqft flat and asked to pay in three instalments. During proposing this they told that amount is tentative and may get reduce in future as BWSSB(The Bangalore Water Supply and Sewerage Board) will inspect for area of society and provide demand note(cost break up).

Even after three months of proposing this(In Annual Genral body meeting or AGM), there is no clue of inspection date and demand note. They have raised invoices(first instalment) of amount. As demand note is not generated and final amount is not yet cleared to us. I am not planning to pay this until demand not is generated. As this may block my money for unknown span of time.

Due to this they are threatening to stop all the services(maintenance related) for which i have already paid(maintenance fee). our Byelaws says that maintenance related services will be stopped if maintenance charges are not paid. But Kaveri connection comes under Capital expenditure which is not related to maintenance and Why i should pay when govt itself has not generated cost break up.

Could you please guide, What kind of legal options are available for me as this is purely extortion and mental harrassment.