Cash send *****

I sent a cash send of 1000 to my sister on the 15th of August 2019 at 18:03. She then told me on Monday that when she went to the atm she got an error message that said invalid. I then called the call centre and was told the money was withdrewn at 18:13 on the same day at Cape Town. How is that possible, how did the person get the withdrawal number when the sms was sent to my sister. I then went to Maponya mall and your consultant didn't know what to do but I was told by the call centre to go to the Branch for further investigations. ABSA please let me know how two people managed to get an sms about the Cash send when I only sent to one person? I want my money or I will take this further cause I really does not make any sense how this happened.