Unauthorized debit order by MTN

I signed up for a new MTN contract and clearly marked EFT as payment method. I noticed that the first invoice I received was marked as debit order. I emailed MTzn and the business email address several times, with no response. On Thursday I called 135 and advised that I did not agree to pay with debit order and I want to pay using EFT. The consultant confirmed that the debit order was canceled. I paid the full due amount to MTN via EFT. MTN took the money off my account last night and caused my insurance policy to bounce but MTN managed to get their money - Now my account is overpaid by R1036.46 and I have unpaid debit order fees on my account. How is MTzn going to remedy the harm caused to my banking profile now that I have an unpaid debit order reflecting on my history.