Telkom *****ing my money

I have a contract for mobile data with Telkom. I am trying to cancel it. I phoned Telkom and they told me I can't phone and cancel it, which is ridiculous, I have to go in and cancel the contract. I went in and cancel the contract and got debit the end of the month so I phoned them and they told me it is still active, but they will get back to me. they never did. I have probably phoned 5 times and every time they tell me it is still active.