Please tell me I am not wrong in this...

Ok so had this "debate" with a co-worker. (ok it was the guy who does the collection calls so I don't want to get him to irratated or else he will quit then I have to do collection calls)
So he talked to a customer of ours who was originally being billed on the 25th of the month automatically.
This customer wanted to switch to the billing date to the 5th of each month. This conversation took place on the 21 of the month. So as I see, the customer was hoping to avoid a month's payment by pushing the payment for the 25th to the 5th. Which is all fine and dandy, but Mr. Collections did not see why we would need to either bill him twice on the 5th- once for the month he pushed back payment (June's payment) and then for July's payment. Make sense right? Just because you change your billing date does not mean you skip a payment.
If you tried to pull that with a cell phone company it would be the same thing- if you pay your bill in July, you still had service in June.
But Mr. Collections acted all put out that I told him we would still have to bill the customer on the 25th since he had not paid for June yet- or that he would have to be billed twice in July... PLEASE tell me that makes sense and I am not the only one who thinks that way.... By the way if you need a mental image of Mr. Collections- think something like this... very similar- minus the cheesey smile cause let's be honest he is doing collection calls and no one doing collection calls is that happy-- but the hair swoop is pretty acurate