Early debit order deductions

Standard bank has decided for some reason to start debit my account early on the 23 of each month and not on the 25th as agreed. So every month when they debit me early they take the last money I have left before I am paid. Last month i spent a painly 3 hours on the phone trying to get my debit order date adjusted to the 25th of each month and the agent confirmed it was fixed. Surprise , surprise they go and debit me again early this month . What is the point of 3 hour call to fix what they changed without my permission in the first place . Come on standard bank is it that hard to fix my debit order date even after I called you last month!!