Unauthorised Billing

I have just been billed R3220.46 on 28 September 2017 by FNB from an account which they didn't ask me permission to debit from that account was set up to put funds in there to pay off my bond. How can they just debit any account of yours without consent so imagine if they are taking 5c from everyone's accounts without us knowing this is madness. the worse part is when you try to call them and sort things out you get put through from pillar to post hold the line for 10min get through to an operator who tell you to hold on for someone else then the call drops. I am so tired of ***** National Bank(FNB) when you owe them money they will call you 50 times a day but when you need to rectify something they don't give a **** cause they have your money. I feel like changing banks cause this is total bull****.