Incorrect acc number

I made a transfer using my capitec app to std bnk acc,unfortunately i punched wrong acc number the money R400 went to wrong std bank client account,i tried to make a recall with capitec nd capitec told me i cnt do recall bcoz i made an immidiate payment to that unknown client nd the told me to go open a case bcoz they cnt help me any further,then i went to std bnk nd they told me they cnt help me bcoz m nt their client nd they cnt go into their clients account without the clients consent nd they are not even allowed to contact client on my behalf i must go to my bank for help