debit order to move no one can assist me

After numerous calls no one can assist me, our debit order goes of on 29th of each month I have been asking to change it to the 1st because my money is only being paid the last day of each month. I also have a new bank account and no one helps me to change it! Then I have to get sms's saying I am in arrears etc! This is unacceptable for me. Please someone assist me