Unauthorised Debit Order

My rent money which was transferred to my account was taken 5 seconds later by FNB. It was not a salary and they deducted the money and will not reverse it as requested.At the moment I am unemployed and FNB will not accept the amounts I can afford to pay towards my account. I want my rent money back!! The call centre staff all have an attitude and when I asked the so called supervisor for her details her response was \oh gosh"is that really how you speak to a customer. I would understand if this deduction was made from a salary or UIF payment made into my account but it was not!"""