What is the more polite way to say “This is not my fault; you are the one who put in the wrong order.”
I'm sorry. You put the wrong order in. It's your fault, not mine!
I sincerely apologize for the wrong order. I will put in the new order immediately.
While I sincerely understand your frustration, I regret to inform you that the order has been put wrong in the first place.
I wish you would understand my point. This is not at all my fault, I would like to help, but since you put in the wrong order so you should solve it too.