Check if you are confusing your C&C:Online password with your Revora forum password.
Thanks for the reply.
I've changed the username and password on the cnc-online site, now if I use my old username/password I still get the error "A Profile with that username already exists" when I click on "Login"
When I try the new updated username and password I get an error "Could not connect to command and conquer online", but when I give it an incorrect password I get "Invalid username or password" so it does try to authenticate, but when the details are correct I get that the service is offline.