Xfinity has my current modem mixed up with my old one that I need to return.

Hi Xfinity,

Right when covid hit I swapped my old modem for a new modem. I wasn't told to return the old one so it's been sitting (or I overlooked that). Recently I've noticed a 14 dollar unreturned fee for the modem.

Here's the issue:

Old Modem has been unplugged since early this year. 

New modem was activated (I was able to get into it etc and setup wifi). Xfi was working.

Now when I go my Internet Account info page it shows that my OLD modem, which it thinks I'm using, is offline (cause it is) and that my NEW modem (which I currently use) needs to be returned.

10.0.0.1 gets me into the NEW modem. But trying to manage it via Xfinity.com says "Your Gateway may be offline" which it's not because I'm using it right now. 

This happened sometime in the last few months. 

XFI no longer works as it thinks my OLD modem is the one thats active on the system and it says its offline (cause it is). 

My issue is that I'm afraid if I return the OLD modem my NEW modem will stop working. I do not want to get into a wacky situation where my internet is down for days and I can't work. I talked to a nice rep and she seemed confused.

How can I return my OLD modem without jeopardizing my internet? I also want to get rid of that 14 dollar fee.

TLDR;

New Modem was activated and is STILL working. 

OlD modem needs to be returned but system prompts me to return NEW modem. Thinks old modem is the current "active' one but offline. 

Extra TLDR; New/Old Modem swapped in system. How can I return old modem?

Thanks All!