Mtn just tell me why you charging me extra

All I want to know is why I am being charged a R100 extra on my contract. But the verification process, I don't feel safe giving out all that information, so I filled in what I felt safe giving over email. But your people keep asking for the other info. So please I just need to know something about my account not upgrade or change anything. And also come up with a better verification process like maybe a 2 step verification process. Regards