MFC changes debit order date

MFC is driving me nuts! I have bought 3 cars through them now, and every time I have to fight the same battle. I get paid on the 25th, but they keep on making my debit order date the 24th! I phoned this morning, was told that they will amend the date, and 10 minutes later got an sms to say the date has been changed to the 24th! I phoned back and spoke to a disrespectful consultant named Bridget Masimdi who couldn't help me. This is the last car I am buying through MFC, that's for sure!