Capitec Bank poor service

My younger sister accidentally transferred money into a wrong account via mobile banking, she put the incorrect cell number by mistake, then she called Capitec bank to ask them to please reverse the transaction for me, she was advised they need permission from that person to reverse that money, but the other party is not answering the phone that was on the 11 March 2018. My sister than called the number where the funds where transferred to, the person confirmed that they received the funds the bank can call them back. My sister went to the bank this morning and they said she must come back after 3 days with no explanation or what so ever she was just told that the have opened a case with the incident department.

Please help and advise the procedure in solving this matter.