incorrectly debited my account

FNB credit card debited my debit card to pay off my credit card whilst the credit card was paid. I spoke to Penelope who confirmed it was a system error as it had done that on multiple accounts for different clients. I advised them that i needed my money to use it urgently and was advised they cant promise anything. I requested a call back from her supervisor by 12:00 noon yesterday and until now i'm still waiting for my money. I'm stranded and my so called bank has my money. This is despicable and not acceptable. I want my money A.S.A.P