Cell c Content services

So I recently ended a contract with cell c . The sim and the number was ended. I am now getting a bill every month of R73.08 for "Content Services" Call center told me I can only cancel it if I call from the cell number but I KEEP ON TELLING THEM THE NUMBER DOES NOT EXIST ANY MORE. I have been to a cell c store but no one can help me. This is the worst service I have ever gotten from a services provider. SHOCKING