Hi Chief,
Thanks for your message, and sorry to hear about your difficulties changing your name.
Clash of Clans is an international game, and that's why we check the suitability of usernames in a variety of languages. If the name you've selected isn't valid, it means the name, or some part of it, is blocked by our language filter, or the name's format otherwise does not match the username requirements.
Please try a different name, or a different spelling. Avoid using emoji or other special characters, and remember to keep it to a length of 15 characters or less. That should do the trick.
Clash on!