Debit my account without my permision

I have a credit card with FNB, which i have been struggling paying off. I have made an arrangement to pay in small installment with a possibility of me settling it by April. I made a payment of R300 yesterday and was going to make another payment of R300 today. I woke up and an amount of R1380 has been deducted from my account without my permission and with no warning from FNB. This is not the first time this has happened and i feel it is now abuse. <br> <br> I have banked with fnb for more than 13 years and this is the treatment i get. The money in my account was for my child's school fees and our groceries and being a single Mom is very difficult. I wish to settle them but current circumstances are not allowing me.<br> <br> Im very disgusted and angry at this kind to treatment from the bank i have been loyal for so long