Incorrect Debit Order Date

I received an sms a few days ago saying my debit order will move to the 22nd to match my salary day (my salary actually gets paid the 25th) so I called them and told them to move it to the 25th or later cause I don't want my account to go into overdraft unnecessary since there are additional fees. Person I spoke to said they made the change but I was charged this morning (22nd) and now my account did go into overdraft. Don't understand why they randomly decided to change the debit order date in the first place since nothing changed on when my salary is paid