Standard Bank Vehicle Finance debit order error

Standard Bank Vehicle Finance made a mistake when they sent me the initial debit order to approve on my banking app. Now, they keep calling and calling for me to pay for a something that wasn't due according to the debit order terms. I have asked to speak to a manager several times and was told I can't, then I sent an email to their complaints center and asked them to adjust their system because the error was on their side. No response.