Unauthorised journal debit

I am very frustrated with ABSA. Today the collections department decided to do a journal debit for R 2,407 for my personal loan which I did not authorise. They have been deducting monthly an amount of R250/R500 which I did not have a problem with. Now they decided to take all my money taking food out of my mouth. I feel this is unacceptable as I did not authorise any amount for deduction and I need to dispute this. I did phone ABSA but was transferred to 10 different departments with nobody being able to assist. ABSA does not have the authority to just deduct any amount they want. I will take this to the Ombudsman if not resolved