ABSA System can't update debit order details for funeral policy.

I have been calling every month from June requesting to change banking details for the ABSA funeral policy deductions. Every person that I speak to tells me that the banking details have been updated, but every month end the debit order goes off the incorrect banking details. The last time I called I told them my concern is that there'll come a time when they debit and there's no funds in this incorrect account and it won't be my mistake because I followed the correct process and they didn't. The last agent I spoke to i.e. Karl Hilton, told me that he can see two account numbers in their records and he doesn't know why the system doesn't cancel the old one, he was going to query with the tech department. The reason I'm complaining now is because the debit order went off the incorrect account on Monday and came back unpaid. Who's fault is it? Who's credit score is being impacted here? How difficult is it to load the correct banking details so that the debit order can go through smoothly???????????