Im sick of this debit

I have 14 "declined foreign t 457" transactions that cost me R8.50 each in the past week. I don't understand why FNB is allowing that to happen on my account without letting me know what it is for!. It is deducting money from my account without any permission! Everytime when there is money in my account it deducts -R8.50 per day,even when there isn’t money which leaves my account on minus. it is costing me to lose money for something i have no idea about.