Accounts department-debit order not done but handed over.

Please look into your accounts department. I cannot be called on the 27th of every other month to be told I have been handed over for a debit that was not taken TWO days prior, yes on the 25th. No one knows why the debit order didn't go off when I make sure funds are enough and to be told my account is in arrears. This happens especially when the 25 falls on weekends.