Incorrect Billing

I've been trying to reach someone at Vodacom for over three hours, but they’ve made it extremely difficult to reach them. Every time I call, I get transferred to their useless virtual assistant and the same thing happens when I try to contact them via email. I need a human to assist with a billing problem, not an automated system. I signed up for a data contract at R479, but I’ve been charged R528. Can you please explain why the billed amount is higher than what was agreed upon?

My contract line is : ***