I have an account with internet at two addresses. One of the addresses disappeared even though I've had internet there for years

I have an Xfinity account with internet at two different addresses. One shows up in my profile normally, but I can't find any trace of the other. Xfinity messaged the users on the internet of the disappeared address saying the account was past due and the internet was deactivated. I'd love to pay and get that internet back online, but nobody at Xfinity can find any trace of the account and they keep assuring me that there's no account at that address....I keep explaining there's been internet there for years and they literally just messaged me about a past-due account. How do I find the information associated with that address? None of the lookup tools are working. I think there's a bunch of old accounts associated with my Xfinity phone number and email and those seem to be mucking up the works as well. Also, wow is Xfinity's phone customer service useless.