Cancellation not actioned

I had already taken out new contracts with another provider months ago and waited out my contracts, on the same day I called and cancelled 2 of my numbers with Cell C on the same phone call with Mc Donald. at the end of last month the one contract was reverted to prepaid and cancelled however the main one wasnt and was converted to month to month, and I only saw this when I opened my statement. I Called in last week and spoke to a lady whom advised me that mc donald would have to call me back and took down my new number as the number is question I no longer use. to today no returned phone call and a bill that is still going to go off my account this month. I told the lady if they debit my account then i'd return the debit order and Cell C would be liable for my banking fees. I want someone to call me TODAY to cancel and credit my account before the debit order goes off.