Absa: Unauthorised debit order deductions.

I have vehicle finance through Absa that is deducted on the 1st of every month as per contract by debit order. This month (December 2023) the deduction was done as usual, but on the 14th December I received a message from Absa that a second unauthorised deduction will be done on the 18th of December. I immediately informed Absa via email that this is unacceptable and as per contract, *******. I was sent a reference number(c-***4) from Absa and on the morning of the 18th visited Absa where I spoke telephonically to an official in their finance dept. She told me that the deduction will be moved to the 29th of December. On the 19th of December I received a message from Absa that I will be referred to the credit bureau because I do not have enough funds in my account. I immediately (+- 9h00) called their finance department and repeated the above-mentioned scenario to the lady who answered. According to her Absa will rectify the situation. Up till now(11:47) I have not received any written confirmation from Absa as to the rectification of this issue. Is it legal for any banking institution to run a campaign to make unauthorised double deductions per debit order?