Debit order ran on the incorrect date

I'm very angry that you decided to debit my account on the 19th December whereas our agreement is to debit my account on the 20th .I want to know who gave you that authority to debit my account on the 19th ,now I'm setting with a returned debit order and I cant afford to have a returned debit order as I'm working in Credit department. I want a written apology to be sent to me before COB Today.