Unreturned equipment notice for modem returned years ago

I recently canceled my service and received an email requesting the return of a modem with serial number TM0245102210. I do not have this device. This was an old rental Arris modem that I physically returned several years ago when I switched to my own personally owned retail modem. Could someone please review my account history, verify when my personal modem was activated, and remove this old serial number from my profile so I am not charged?"