Invoicing Incorrect Amounts

I am now sick and tired of this and this has become my last resort in order to necessitate proper service. I have been, repeatedly billed the incorrect amount, escalated this to Telkom but to no avail. When i called back today AGAIN i found that the issue was not even being attended to by a consultant. My query had just been sitting in Limbo (Waiting for who????) yet Telkom have the audacity to issue a debit order on my account! (FOR AN AMOUNT WHICH IS OUTRAGEOUSLY INCORRECT). Forcing me to have to go to the bank to reverse this. Who will ever accept paying much more than what they have??? It's not my fault that I'm being invoiced incorrectly. And then they have the audacity to send me sms threats of service interruption! Correct my Billing and i will gladly put through the payment. Telkom please get your act together and resolve this issue. This is literally my last straw and i will be forced to cancel my contract.