new bill extra charges

i just got a text message to say that a new higher amount is going to be debited from my account on 30 august, i looked at my invoice that you emailed me and compared this message that i have just received and this message is a higher value. i have phoned 135 now twce, forst time the call got cut after 6minutes waiting and now 18minutes it got cut off. just to let you know that when you do debit my account and the wrong amount is debited off i will reverse it, the reason why i can reverse it is because i control what comes off my account, not you! you can suspend my account u can do handstands if you want, i just go to a mtn pay as u go..... hopefully someone in accounts picks this up and send me a direct number to call.