Contact support and we can see what can be done. Changing usernames is rarely done.
Hey I managed to fix the problem by logging into the Stardock account page and changing my password there to something with less then 12 characters, so theres always that solution for anyone with a similiar problem.
Not sure why you can have a password with more then 12 characters but then cant use that password to change things due to a character limit in the password box? If its possible to increase I think it would solve a headache or two for people in the future but I leave that up to you.
Thanks for the quick response anyway.