This email address is not available for use as an Apple ID. You may already have an Apple ID associated with this address. Please try again or sign in using your existing Apple ID.

Hi billfromwandering,

I'm sorry to hear you are having these issues changing your Apple ID. It is correct that if an email address has been used previously for an Apple ID, it can not be used for a different Apple ID, as noted in this article:

In most cases, your Apple ID is also the primary email address of your Apple ID account. You can change your Apple ID to any other email address you control, as long as it's not already in use as an Apple ID. If your email address ends with @icloud.com, @me.com, or @mac.com, it's already an Apple ID.

Change your Apple ID - Apple Support

If you are certain that the email in question has never been used for an Apple ID and you are having issues contacting Apple Support regarding this issue, you may want to make sure you are going through the Apple ID support channel on the following page:

Apple ID - Contact - Apple Support

Regards,

- Brenden