Cellphone Account more than 500 % above normal acc

I use to have 5 lines on the same account. On 11 Oct 2015, I still had almost 4G left on Data but the very next day I received an SMS that this line has an unbilled amount of more than R11000-00 excl VAT. I Immediately requested Autopage to separate this line with the enormous unbilled amount to a separate account on its own to not affect any of my other lines. They did separate this line but left the other 4 lines with the bad account. I was billed in Oct for R 16040-00 instead of average R3000 / Month. I spoke to Jackie from Accounts ***) and she ensured me that a IT Technician will investigate this matter but I must pay at least R3100 for Oct bill to keep my lines opened. A week later my lines were all suspended and after complaint they re-open the lines just to suspend it again. They now tells me to PAY the full outstanding amount which is totally out of the Question. I am now considering to cancel all my lines with Autopage and go to a new provider. This is TOTALLY UNACCEPTABLE !!!!!!