Mistyped account deposit

I deposited an amount of R3010.00 on the wrong account and immediately I called Capitec and reported the matter that I mistyped the account number and I was given a reference number. After they called me and told me yes they do see the money in the account but they won't be able to reverse it I should go and open a case at the police station. The I went to the police station all they could do for me was the affidavit saying that I deposited the money in the wrong account when I went back to Capitec they said yes they did see the money on that account but they couldn't reverse it because it is a closed account. I don't understand why they can't reverse it if they see the money and they could see it's from me and I made the mistake. If the money was not in the account they were going to say they can't help me because the person withdrew the money but they do see it.