Can't log in to any Xfinity apps on my phone

Ever since moving to a new home, we've had countless issues with our Internet service (mostly in terms of coverage and non-working pods) as well as account info problems.  I suspect that Comcast's back-end systems never truly disconnected our old account as part of the move, and now it's wreaking havoc on our new home's WiFi.

Specifically, I am currently unable to log into ANY Xfinity app (Xfinity connect/xFi, Xfinity Home, My Account, Xfinity Mobile) with my new account into.  For some reason, I can still log into my account using an internet browser.  I've tried everything on my iPhone (clearing cache and web history from Safari, turning off all security protocols like cookie-blocking, etc.) and have even tried another iPhone with the same results.

After spending several hours on the phone today with Xfinity reps - none of whom came anywhere close to solving my problem - I'm at a complete loss.  Please advise.  Thanks.