debit order refund

I currently have an existing vehicle finance with ABSA bank and have come to realise that they have debited my account with extra R862.37 amount for unauthorised debit on insurance. my car has at all times been insured with the same insurance company I supp**** the bank with more than a yea ago and have never changed the insurer, if the bank could go to the extend of enforcing their own insurance on me did they at least validate.they are telling that they tried to get hold of me and I didn't answer my phone...yes I was at work and could attend to my phone. I'm now being told I have to wait for hours before I can get a call from their admin department, I sent proof of my insurance again last night and cannot afford to wait for my money to be refunded. I want my refund done as a matter of urgency, I feel one attend to call and then you enforce the debit order to customer is unfair treatment .