Home Loan Account - Set off refused to be refunded

My std bank home loan account was in arrears for Jan and was supposed to be double debited for the 25th of February. I received a deposit into cheque account in error as the money was supposed to be paid over to someone else and not me, I go into the account to pay it back to find that Std Bank already took the money. .days before my salary and due date. When I called through they refused to refund the money. <br> How am I supposed to return this money...the Bank refuses to give it back. <br> When I called through they say its a set off ...aren't there rules in the Code of Banking Practice that say you should advise the customer of the set off. How can you clear out a bank account with no money left to the customer.???