Have you searched for other posts with similar issues?
This is a common problem with many threads discussing/reporting it. There is a trick to get an agents' attention, however they don't want it posted publicly. You'll just have to be patient for an agent to respond on this forum.
Another poster has stated: "This was resolved by phone with a tech. My credentials were not linked to the proper account after changes were made to the system."
You might also call 1-800-COMCAST and ask if the agent can link your profile login to your account properly. If they cannot, then ask if they can escalate it to the next level support.
Greetings, Soda15! I appreciate you taking the time to reach out to us here on the forums. I hope you are having an amazing day. I apologize to hear you are having issues with getting into the MyAccount app or website (http://xfinity.com/myaccount). That's certainly frustrating as you're missing out on an amazing tool that helps you manage your account. I would like to get you back in there. Can you please send me a PM with your first/last name, user id you are trying to login with, and the phone number that's on the account?
To send a private message, please click my name "ComcastMichael" then select "Send a Message" on the right side.
Hello, Soda15. I have not heard back from you. If you still need assistance, please feel free to start a new public thread.