Foreign Transaction -R8.50

Declined foreign T457 transactions of 8.50. Declined foreign T457 transactions of 8.50 is really becoming problematic for me having FNB constantly deduct money from my account without an explanation at all. My account is sitting on a negative balance due to this and I'm seriously disgusted by this. I have no idea where my money is going or how to stop this. I am really angry because its been happening for months and I have paid thinking it was a once off thing but I have had R8.50 deducted 7 times in the space of 1 day, I am not happy at all and need an explanation and have this fixed immediately.