Double debit Nedbank Homeloans

I have an existing home loan with Nedbank. They tried calling me and i missed the call. I phoned them back and the lady told me i had amount of about 1000 in arrears i then told her after taking everything into consideration to debit me in two parts with my current home loan installment which is 3300 a month. Well let me tell you this they double debit ordered me today. This all after we had made an arrangement to suit both parties. I fee ****** and violated by an institution you should trust with your money. I am gonna close my account with them immediately as i cannot trust them no longer. I mean its January what about school fees, rates just to mention a few. Thank you Nedbank homeloans collection department for making my Day terrible. I need them to look in this matter pls.