Website taken off the world wide web

My website is down. Telkom hosts my website. But the 'server not found' / 'domain not found' message comes up when I or anyone else tries to access my website. And together with that no-one can send emails to me and I cannot send emails because my domain suddenly does not exist any more. No-one at the call center can help or even knows what I am talking about. They keep on thinking my adsl is down or my phone line is down... I received a reply after my email to [Email Removed] saying that my account has not been paid, but it has been paid. Last month exactly the same thing happened to another domain of mine - also paid and not in arrears! Billing department confirms I am up to date. But I cannot get hold of anyone who can put my website back up again. I am losing clients and business! Why do I have to go through this pain month after month.