Change of debit order details

My banking detail was changed on the 6th of September, on the 1st of October it still went off the old account. By inquiring about it telephonic I was told that it was because it wasn't done before the first of the previous month. The more I told the people at MTN that it's not how it work the more adamant they got. Clearly they don't know how to do their work and I know that's not how it work.

Keep that in mind, my debit order went off the wrong account again on the 1st of November.

So I went into MTN Jacaranda, and the lady there told me that my banking info was correct on the system and the problem will be with my bank, because what's on their system is what will be sent thru to the bank for deductions.

Can you believe this *******, explanations.