Unauthorised Debit Order on a credit card that I never app**** for.!

On the Beggining of July i noticed that on my banking App i have an extra credit card that i never app**** for and already it had a negative balance. Called Fnb and they said it is not active and they do not know how it got there. I was told to send an email which was sent on the 11 July and i keeps calling and told about 14 days turnaround. Came months end i debit order went for bank finance charges mind you i do not have the card and it doesn't have any fund but i am paying for finance fees for a card they claim uit is not active. I have tried everything complained everywhere even spoke to the Manger Randy Thompson who promised to call me back and will sort out the matter right away that was Wednesday i haven't received a single call from FNB and that credit card has a negative amount that they will deduct month end again. I dont know how they manage to open credit cards that we did not authorise.