Bank refuse to pay my money

Hello dear peter,on the 16/08/2018 I used my nedbank money app and transfered money 2 my brother's capitec account only to find out that he closed that account BT my money went through I then went to nedbank and they told me I must call their headoffice I did just that but they told me that they don't see any money that was transfered and I told them but how cos I even got an SMS that the money is deducted they can't explain and they are refusing to pay back my money ....the amount was 600 please help