ABSA DEBIT MY ACCOUNT PRIOR TO DEBIT ORDER DATE

This morning I woke up to a shock of my life. Absa decided to debit my account with the Personal Loan instalment a day prior to debit order date. As a result my account was left with unauthorised OD and the debit order was returned unpaid. I am not prepared to pay the unauthorised od and unpaid do charges. Please rectify and return back to me.