You could try quoting the heading of Section 151 of the Strata Schemes Management Act (below) at them, pointing out that they could be breaking the law if they turn off the water (probably not, but worth a try) and that the landlord will definitely be breaking the law if they let them, which should speed up the payment.
151 Owners, occupiers and other persons not to interfere with support or shelter provided by lot or with services
An owner, mortgagee or covenant chargee in possession, tenant or occupier of a lot in a strata scheme must not do anything or permit anything to be done on or in relation to that lot so that … the passage or provision of water … through or by means of any pipes, wires, cables or ducts for the time being in the lot is interfered with.