Joining fee when no alternative supplier is available?

Hi guys,

Just moved into a new apartment and the heating and water is supplied by a single supplier who has a contract with the owners of the complex.
They are requesting a joining fee even though I have no other choice of supplier. Is this legal? Surely if I am being forced to use there services I shouldn't also have to pay a sign up fee for do so?

thanks
emc2

Did you buy or are you renting?

Renting.

What does your contract with the landlord say about these charges? All this should have been agreed before you signed the lease.

Is the fee a 'joining fee', or is it more a bond put in place to protect the supplier in case you skip out without paying the final bill? What supplier is it?

It's a Joining fee, there was also a security deposit which I am fine with but this fee seems to be for nothing really.
There's nothing in the lease about it but the heating/water system is overall system for the whole complex which is managed by one company. I can't get another supplier.