Autopage claims outrageous data usage

I received an invoice with call charges amounting to R983,33, making my total bill R1241,39. This call charge was on 1 day, in a single data session. I am always careful to not go over my allocated data, hence I know this is a mistake on Autopage's side. Upon complaining via their website, I got an email with a reference number and then another saying the dispute has been closed. They claim I used 7gig data. Complete & utter nonsense! The EXACT SAME THING happened last month. They have not, up to date, provided me with any proof or explanation of this. May I remind you of the Consumer Protection Act, no 68 of 2008 - in which people like myself are protected and can depand proof of such outrageous claims. If Autopage fails to produce concrete proof, I will be forced to take matters further.