How is it being blocked for you to see? Are you logging in as the account owner? Are you getting some error message? What if you log in using a web browser to the MyXfinity.com web site?
How are you logging in and on what device? If a mobile app, if you uninstall it, when re-installing, it should allow you to use the correct user name for the account holder assuming you know what it and it's password is. If using a web browser on a PC or Laptop, logging out of the MyXfinity web site should allow you to change logins to the correct one for managing the account. If somehow your login's are messed up, you might need to call 800-COMCAST or 800-XFINITY to talk to an agent.
Hi Yommer, thank you for reaching out here and I am sorry to hear that you are experiencing difficulties trying to log in and pay your bill. If you still need help I would like to assist in troubleshooting this further, please send me a private message with your full name to begin.