Overcharge

The normal thing to do is to purchase a phone to replace the one that got lost and have a replacement SIM card made for the number.

AT&T didn't do anything wrong.   You had to ask them to cancel the line number. 

Lost, broken, or stolen devices also do not relieve you of any installment payments or contracts that are on that line related to The Lost stolen or broken device.

MicCheck: I did not tell them I didn't want to keep the number. I don't remember their reasoning for this but I DID tell them we lost the phone, needed a replacement (which I has to purchase at the ATT store to get it right away) and to cancel the other number when they assigned the new number. This was all done at their direction.

The only way to cancel a phone number is to call AT&T. You cannot cancel a phone number at an AT&T store. From the description of your transaction, you should have called AT&T back once you had purchased the new phone.

I still don't understand why you would cancel an existing line, rather than just purchase a phone outright and have a SIM card made to replace it on the existing line.

Hi lizdance40. i did this all over the phone with them except that we had to get the phone from the store. I followed their direction; I didn't make the decision to cancel the existing line on my own. I would rather NOT have had a new number but that isn't the option/direction I was given. As I've never lost a phone before, I wasn't aware that the direction should have been questioned. What would actually be helpful feedback/advice/comment would be to help me see a way to get in touch with them instead of questioning what I did and why. What good is that? What's done is done - again at the direction of AT&T.

Where are you still paying AT&T or still under a two-year contract on the phone that was lost?