WRONGLY CHARGED FOR DATA

I have a date contract in terms of which I pay R199 per month for 10Gig of data. On the two previous month's invoices it indicates that, in addition to my normal monthly subscription, I bought additional data. When I enquired with the call centre, I was told that the data was bought by using the app or the internet portal. I do not have access to either and did not buy any additional data. I do not even know how to purchase additional data. I was then informed by the call centre agent and her manager that according to the system I bought it and there is nothing that could be done. However, I insisted and the manager informed me that the technical team would investigate and provide feedback. It has been almost two weeks and I have not received any feedback. I insist that the matter be properly investigated and feedback provided. I will not pay for data that I did not buy!