Unauthorised debicheck debit order

I deposited money into my nephew's bank account unfortunately there was an unauthorised debicheck debit order which debited the money, i asked him to go to Capitec for reversal when he got there they told they cant reverse the money he must contact clientele, but clientele said they cant reverse it Capitec should assist with that. We are being taken from Pilar to post for a mere D/O! How is it possible that they cant reverse a debit order that was not authorised? I am very dissapointed!