MTN Debiting Account with new amounts and without notice and Approval

Appauling customer service and billing. I was on Mobile Data contract for R369 per month. At the end of the contract I was informed that it is now month to month and will be billed without any promotional rates. There was no information as to what the new rates or data bundles. I was then hit with a bill of over R1111.56. I then treid customer care and was on call for over 20 mins withouth any answer, I then wrote email to customer care to cancel, to which I got a response to say it handled to cancellations and then the ticket was closed. My account was still debited for R1111.56 wihthout any approval from me and with my cancellation request with cancellatios department.