Need to verify contact info, yet unable to verify contact info.

My current address/roommate previously had an Xfinity account which seems to be confusing Xfinity and its billing options. Sometimes it says I'm not signed up for Xfinity Now at all, even when the app on my phone and the modem in my room are connected and I have the receipt to show I'm paying for the service. Any attempt to view or change payment options/billing history gets me the "We need to verify your contact information to keep your account secure. Make sure to add your phone number and email address if you haven't already." error. Attempting to verify my contact info (because both are already added) just gives an error about it not being able to be completed. I've tried multiple browsers, different PCs, my phone, cleared browsing data and talked to associates in person who swore everything looked "fine" and all previous accounts were closed—the issue persists.