Complaint: I am still being billed 5 months after cancellation

My daughter has cancelled Rain Wi-Fi for the past 6 months, and to my surprise I am still being billed for the service. This morning I was debited with R479-00 by Rain for a service that was long cancelled . I am tired of paying banks charges for something I don't use. Can someone explain to me what is happening as I phoned Rain to find out and I was told that you have to pay that fee after canceling!! I have no active purchase agreement with Rain and they don't have a right to debit me as it was a once off-thing. I am going to write a complaint straight to the the Consumer Protection Board, I am really tired of paying the banking charges for transactions that are declining!!! please they must just leave my account alone!!!