ATM incorrect deposit

My wife went to make a deposit at FNB forest hill mall. Unfortunately the money was deposited in an incorrect acc, mife is now in the centurion FNB branch with a deposit slip. she was told that funds can't be reversed, they have to call the account holder so that she can withdraw the money and deposit it in the correct account. Shocked!!! I have never heard of such. Why can't FNB, reverse the transaction whether or not it was deposited at the ATM.that transaction can still be traced, as there is proof of payment. And it was done at their ATM and there is a deposit slip with details I find this strange I see a person passing a buck and not willing to go an extra mile or willing to assist. NOOO FNB, do something