We have received info from our ISP informing that Melbourne IT require =
  us to pay some extortion or they will deregister our domain name.
  

Wilson, I understand your ire, but this is a travesty of what Melbourne IT
will have said, or what lies behind their action. I really suggest we try
to avoid imputing motive.

I think their costpoints are wrong, and their model of fee collection is
wrong, but I do *not* think that your name is viable and active in perpetuity
without some maintenance costs. If you haven't been paying any, doesn't this
suggest you too have been rorting the system?

If you go out and examine the issues, I suspect you will find that registration
and ongoing re-registration is very common. Of course we all need to know what
the money gets spent on, but that doesn't invalidate the requirement to pay
towards the costs of making names (and in this internet case) addresses work.

cheers
	-George