Nedbank home loan debit order date changes without consent.

Nedbank has been most useless over the last few months. They have change debit order dates without my concept and it is now months later after calling for hours to and get my date back to pay day. They made the deduction in the middle of the month and now towards the end of the month and each month I am surprised at date. No assistance has been provided as it is their new system which they have implemented.