Cancellation not done

My son has gone overseas so instead of renewing the contract I cancelled it and wanted to change to prepaid. I phoned cancellations on 29 October at 9.34 am and was told that it had been done as requested. I expected to pay for another month as it would be 30 days notice but end of December was still being charged. Called again on 8 January at 8.51am and was told there was no record of my cancellation request. I asked them to please retrieve the voice recording as evidence that they were at fault and was told that it would take 48 hours and then Precious would phone me. It's now a week later and no further word from Cell C. It really shouldn't be so difficult to do such a simple request and the frustrating thing is you can't do it face to face in a store, you have to phone the call centre and hope they do. It shouldn't be necessary to do follow ups and waste my time. Come on Cell C we've been customers for more than 10 years get it right please.