Debiting my account without a notification

I am honest not happy with FNB. R1700 was debited from my account. I then received an sms from FNB home loans, thanking me for the payment. When I called FNB Home Loans, I spoke to Lerato, then transferred to Palesa, then someone else in the collections division. She then explained that the money was debited at her Manager Charlotte's discretion. My question is, why was I not notified that the amount would be debited as I would have make provision for it? I had my last R1800 in the account and FNB just debits my account and then thanks me for a payment I was not notified of, a payment I did not agree to nor authorise is unacceptable. I was told that Charlotte would in contact with me and I've been waiting for her call since the 4th of March at 11h00. If this is how customers are being treated, then maybe I should consider another bank! This is just unacceptable. Communicate with your customers, don't just do as you please