The situation is: we have new invoices but on all of them the term period is from 09/07/2009 till 09/08/2009Everything has been paid before 09/07/2009 but the servers don’t work and they won’t until we pay the new invoices. Is it right to do so?
As Jason said it is batter to contact their billing department and try to resolve your issue. You have the right to ask them why your servers are not accessible, as a paying customer. Was there any issues other than billing?
If a provider can not explain to you why this is, or when you are unhappy about the policies they have, you should look for another provider. While this may sound harsh this is the way it works.
Of course a company can not refuse your services if you payed for it already; but i have the feeling there is a bit more to it, maybe you should tell us what really did happen to give you a better reply.