REFUSED TO REVERSE THE MONEY SENT TO AN ACCOUNT BY MISTAKE

My sister sent money to the wrong account number by mistake and she called the bank the same day to report this and ask to have the funds reversed when nothing happened she went to the branch and showed them proof and everything and asked them to assist her because that was rent money for our little sister but the bank refused to say they are closing her case because the person who received the money's phone was off. She had proof but they refused to assist her what kind of a bank is this now a child will be left without a place to stay because people are greedy out there I'm very disappointed as to how you handle this while my sister had to skip work to come to your branch. She was giving this stupid case number ***2. You are such a stupid bank and maybe you should go out of business because you are useless I don't want this case closed.