Compensating tenants for loss of heating/hot water

Other

I have an ex-local authority flat let to tenants. The block is fed by a communal heating and hot water system. At the weekend there was a major failure of both boilers and all of the occupants in the street have been without heating and hot water. The council (Wandsworth) are trying to effect a short term repair but they acknowledge that a whole new bespoke system will have to be ordered, built and installed. This could take some time. In the meantime the tenants have been very understanding about the nature of the problem. However, I will need to seek redress from the council and I am concerned about how and to what extent I should compensate the tenants. The charge from the council is roughly £70.00pcm for heating and hot water. The tenants are on a standard AST. I am trying to guage my level of liability.

Any views gratefully received.