Telkom Billing disaster

I had a 2year contract with Telkom that, I wanted to cancel 5 months before its maturity date of July. it took 6 months of going from pillar to post, and they even went as far as renewing the contract on a month to month without discussing with me. In June, i took another contract for Mifi router for R149.00 as per aggrement with Cell direct. But to my suprise, the bill comes to a staggering R649.00. I have tried again, since Aug to correct this. But my account still gets debited with the extra R500 they claim is automatically added to the contract over and above the amount i have signed for, and this without any discussion or agreement with me. 3 Months later, im still being billed for something I did not agree to. why would it take 3 months or 60 day to amend the bill as per a customer's request, is this a ploy to continue milking me for a few more months? I'm really dissapointed with Telkom. I'm losing faith in their business ethics.