Canceled contracta

Have had cell c contracts for about 7 years now but extremely disappointed with service, I have cancelled all lines with them, I was assured that my month to month data contract which was cancelled on 04/08 would be cancelled 04/09 and data would be calculated pro rata, however I am being charged for the whole of September, I even double checked with consultant when I called to cancel my other line on 24/25 August, he said it would be pro rata, now when I called to check why I'm billed in full, this new lady I spoke too says its billed in full regardless and they advise you to cancel @ month end, absolutely ridiculous that I was not informed and when I asked to speak to a manager she said that wasn't possible, matter can only be escalated and I should be contacted in 2 working days. Terrible service after being a cell c customer for years, will never use them again