Vehicle debit order

Absa vehicle finance did me wrong. They debited my payment from an old account (Capitec) that I changed 8 months ago, then I called and asked them not to debit again from the other account( FNB), but they did and the payment bounced. After few days they returned the money to the capitec acc, I called and wrote an email, they told me that they are having systems problems. Now m getting calls from them saying that I missed my payment, so should I suffer for their system problems? Should I have a bad credit record because of their system. This banks are abusing us, now m being called countless times as if its my fault. This is going to end very ugly, I refuse to suffer for Absa's carelessness, a good credit record is very important for a black child.