Still being billed

My mobile contract was up for long way up for renewal, so visited Telkom at centurion mall but have been advised that there is no stock on the phones I am interested in and there is no ETA. So to avoid unnecessary charges, I decided to cancel my contract and migrate to prepaid in the meantime, so I was told that end of October 2015 will be my last debit order.<br> <br> End October 2015 my debit order goes off but now I received an Invoice for End November. I don't mind being charged for services I have used over and above my contract which is only R39 but they charging me for the phone, CLI and package plan.<br> <br> Tried calling them and held on for 40mins and then hung up.<br> <br> Telkom please sort this out before I jump ship completely, I have proof of cancellation. And how can you charge me R468 for a Samsung pocket plus when our initial agreement was R109?<br> <br> People always asked of my experience and I always promoted you guys and now this????