Honoring transactions fees

I am not happy with FNB services. My account is on a minus because they decided to honor(pay) my transactions for debit orders that i did not sign up for. Then charged me ridiculous amount of money for paying on my behalf. I never asked FNB to pay money on my behalf since I don’t have overdraft. I paid over R 1000 for bank charges to thank them for paying on my behalf which i never asked for assistance.