Apple ID email change

Was there a question mark next to it? See if this helps.

When you change your Apple ID, you can enter another third-party email address. Or you can enter an @icloud.com, @me.com, or @mac.com email address that's already a login alias or alternate Apple ID for your account. To see these addresses, sign into your Apple ID account page. Click Edit under the Account section to reveal Reachable At. In this list, a login alias will have a  next to it which, when hovered over with a mouse pointer, shows this message: “This is an alias of your Apple ID email address.”

Apple ID Name Change

there is a contact link.

Apple ID Support

Apple ID Support (2) 

Apple Support by e-mail or chat    Work through the screens to get a chat option.  You may need to pick a problem that is slightly different than yours to get a chat option.  

Apple Support using Twitter

Or fill out and submit this form.          The form is for iTunes, but it will get passed to the ID Support section.  

If this is an alias you created, you can't use that. When logged into the link I posted, you can only use the @iCloud.com address that has a question mark next to it. Is that the one you are trying to use?

Change your Apple ID - Apple Support

Does the address you are trying to use show here?

Apple ID - Manage

You are welcome.