Cancelled contract but debited again

On the 18 of September 2017 I called and cancelled my contract with CellC, they advised that the last debit would be in October. I have been debited again in November for the SIM, which I've never used since taking out the contract.

I called CellC and they are now attempting to find the call recording as they state the contract was never cancelled.

The Ref no. I was sent when I cancelled the contract is ********** ********** 89, they cant even use their own reference numbers to pick up my request on their systems, so what's the point of the reference number.

I will never take out a contract with CellC again.