FNB Took money from my account and gives stories that don’t make sense.

On 8th this month R500 was taken from my business call account by fnb and they said some had filled a complaint on the account so they are investigating, but that money was taken without my permission and the worst part is that it was taken from an account that i have never shared with anyone so i started asking them via the app that how is it possible for someone to complain about an account that only i and the bank know exists and again the account that i can’t deposit on or even withdraw because its a call account. But upto now they are not refunding my money and they keep giving me stories, only one lady gave me the case number “ ***” but later then they said its for the complainant which doesn’t make sense to me because the account cant be deposited on or eft on by someone else but me. The R500 they took from the account they made sure it doesn’t even reflect on my transaction history so I wasn’t supposed to notice its gone. Sorry for them i new how much i had on the account and something didnt addup.