Unable to Log In to Account or Find/Change Xfinity ID

Hi, I recently tried to create a new account and sign up for internet, but whenever I sign in with my email (or phone number or username) and password, the message, "Hmm, the page didn't load correctly" appears.  If I go back to www.xfinity.com, I can see my first name instead of "Sign In", but clicking on "Account Settings" displays the message, "Sorry, A communication error has occurred. We have been notified and are looking into the issue. Please try reloading the page or coming back later."

So far, I've tried:

• Logging in after clearing my browser's cache and cookies.
• Logging in using a different browser after clearing its cache and cookies.
• Logging in on a different device, and on a device using cellular data instead of WiFi.
• Logging in from the mobile app.  After entering my username and password, I get the message, "Access not Authorized.  You signed in successfully, but you must be an Xfinity user to enjoy this service."
• Finding and changing my Xfinity ID.  When I try, I can enter my phone number or email address and receive the code, but after entering the code, I'm told, "This information doesn't match our records."

Any help you can give me would be greatly appreciated.