Overcharged for FREE Facebook

I queried my account for July which I noted was exactly R400 overcharged. I then sent a query to the accounts department and they did a data validation. A consultant came back to me today telling me that the validation was VALID and she rudely informed me that I would be liable for the R400. I asked for the data report to be emailed to me. I then sorted and added up all my data usage. What I noted is the charges for Facebook which is supposed to be FREE. <br> <br> I would like this overcharge to be rectified as it goes against the Cell C public policy - [URL Removed] <br> <br> I have cancelled my account and would like the money back before the 19th of September. <br> I have never encountered such incompetence.