Modem MAC address stuck on unknown account — need de-provisioning help

Hi, I’m hoping the support team here can help since phone/chat agents haven’t been able to resolve this.

We moved to a new address 2 years ago and have had working Xfinity internet since, using our own Netgear modem. Today our account was showing as inactive — I was told the original account was never fully completed at setup (the “purchase/transaction” was never finished), even though we’ve had active, paid service for 2 years.

A rep activated a new account for our address, but couldn’t add our existing modem to it. I was transferred twice more, including to technical support, and no one could add the modem — they said it’s already linked to two previous accounts/locations and is still attached to something, but couldn’t identify which account.

Can someone look into de-provisioning this modem’s MAC address so it can be added to our new/current account? Happy to send account details and the modem’s MAC address via private message.

thanks for any help