Possible ***** within Standard Bank

So I transferred 2 amounts from my ABSA account to my sisters Standard Bank account, without knowing that Standard Bank had closed her account. Normally when this happens, the funds get returned to the account from which it as transferred from. Not so with Standard Bank. Not only did the funds not returned, it seems to have vanished. All attempts to get Standard Bank to resolve the issue has been unsuccessful. My next step is to open a ***** case at the SAPS, as I now suspect someone within Standard Bank have stole the money.