I can't create an @icloud.com email address

Hi all,

I'm trying to migrate from Google and Yahoo to iCloud, but per the subject line, I get stuck in an infinite loop over here on the Choose an iCloud email address panel.

Predictably all the addresses I want to use are already taken, but when I do get one I'm happy with, I get to the Create name@icloud.com? panel which informs me that I cannot change the email address after creating it. If I press okay, it just takes me right back to the Choose an iCloud email address panel and I can't progress!

I've rebooted my MacBook, tried it on my phone, but no luck!

Any advice would be appreciated as this is a rather urgent matter for me.

Thanks in advance!