A **** company debited my account twice and FNB is refusing to reverse it

My fnb account was debited twice by a company called NPLTA Debt. I don't know this company and did not authorize a debit. I went to the bank to request them to reverse it and I was told that I can't dispute it. I'm confused and upset, how can my bank fail me over ****s. I need thorough clarity from FNB