MEMBER NOT FOUND

For approx 2 months I have been receiving the error message "member not found" while attempting to log in. I have changed passwords and logins, re registered, tried different browsers and after 5 seperate phone calls to help center, the has not been fixed. I have been told every time that my issues would be forwarded up to IT which has not reached out or fixed issue. I curious if anyone else has experienced this issue.