FNB FOREIGN T 457 UNAUTHORIZED TRANSACTION

I've had MORE than 10 "declined foreign t 457" transactions that cost me R8.50 each in the last 2 months, makes my account end up being on a minus. 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, it is costing me to lose money for something i have no idea about.im highly irate as i have called several times and this still deducts every single day