Legal Department debit to my savings account

On 18 April I opened a Ke Yona Bundle Account. on 21 April Nedbank legal department passed a debit of R3750.00 to my account. when I queried the debit I was told it was for a American Express Credit card balance outstanding since 2002. I explained to the clerk that i have never had a credit card with American Express. I was advised by him to open a ***** case at the police and submit a sworn affidavit to Nedbank legal. How do i open a ***** case against a non existant entity? and why was I not contacted by Nedbank before the debit was passed to my savings account, and why have I never been contacted about the outstanding American Express balance? My phone number has not changed since 1998. I have also obtained a TransUnion credit report which shows no bad debts or slow payment complaints against [URL Removed] on Nedbank how can you just debit a persons account with a sum of moneywithout letting the person know and then refuse to reverse the debit and expect the person to open a ***** case against a non existant entity? Please reverse the debit and give my money back as it is obviously an error on your part.