Unexplained Charge That Costs R400+ Despite The Data Not Even Being Actively Used

I have a data sim card with Telkom that is supposed to cost R69/m, but for some reason (and the useless customer service agents can't explain why) I'm being billed R400+ every month despite the fact that I don't even use it.

Telkom, I'd love to hear you explain your way out of this one.