Debiting my account for a phone I don't have

Cell C has been debiting my account for the past 9 months for a cell phone that I do not have. I took a phone but sent it back within 2 days as I was not happy with the phone. I was advised that their system shows they have received the phone back and yet they are still debiting my account. I have called them numerous times to try and sort it out and every consultant has told me that they do not pick up my \case"and yet every single time I have called a \""new case\"" was opened because they coincidentally could not pick up anything else. This has been going on for 9 months and I am sick and tried of going back and fourth with the same thing. Nobody has contacted me to advise the progress of the investigation and I constantly have to run after them. """