Money without permission deducted from my FNB Account

Money (without any arrangement) deducted from FNB Account I'm very very upset and unhappy with FNB. Knowing that I owe them money on my Personal Loan I didn't want to escape from my responsibility. If one track my previous payment History with FNB it was really good. But then I started to experience financial difficulty and didn't continue with payments. I also have People that can witness to this. So now JUST BEFORE CHRISTMAS TIME over R20 000-00 rand was taken from one of my other Accounts (with FNB) without talking to me to arrange etc. I was to still make arrangements. I couldn't really pay previously as I used the money that I received to make a living and to pay for rent etc. So WHY (JUST BEFORE CHRISTMAS) they took all my money and left me with just over R100???? That money was to still buy food and to go towards my Rent. I'm really not happy with FNB and if they don't rectify this and get back to me, I will consider it strongly to remove my Business from them. As said I was still to make arrangements. I just receive a SMS from them and the next day almost all the money was taken from my Bank Account. I think this is not human.