Cannot cancel service from Afrihost

I have an Afrihost account which I am trying to close because I moved to an area where they do not have coverage. Confirmed this with them. However, I cannot close my account because there is an outstanding balance. I phoned them in last month to cancel, but they cannot help me telephonically. I have to do it online. I have very poor reception and very limited connectivity on this side. Why can I not cancel telephonically? The worst is that they deducted the new month today, so I am now paying for the second month without service,,,