MTN debit order issues

MTN het systems issues with Dt orders on 30th Oct & 1st Nov.. On the 3rd I phoned them after receiving a SMS confirmed that my account is in arrears an my services will be canceled. I phoned the call centre that at that stage did not admitted the they the error is on MTN side. I was told by the MTN "Service Campion" that the error is on my side as there most probably were not sufficient funds on my side. I asked to speak to a manager & were told that a manager would phone me within next half hour. Well it is now Saturday evening & still waiting. I paid my account via the MTN app option. Only on Friday MTN admit they had issues with Dt orders & clients that already paid accounts would not be debited. Well they debited my account no Saturday evening at 8. I phoned the call centre to be told that no manager is working & I will only be refunded between 7 to 14 working days. Also been told that I have to phone tomorrow again to speak to a Manager. Also can they not log an complaint as it take 2 working days for funds to reflect on their side. I have proof of all the SMS & payments made & they still refuse to log a issue. Not only is this effecting my Credit record just think how much interest are MTN making only refunding clients that already paid only, after 7 to 14 working days.