The email address you're trying to use apparently is being used by someone...
You should probably contact Apple's account security team directly.
Contact Apple for help with Apple ID account security - Apple Support
The email address you're trying to use apparently is being used by someone...
You should probably contact Apple's account security team directly.
Contact Apple for help with Apple ID account security - Apple Support
The email address you're trying to use apparently is being used by someone...
You should probably contact Apple's account security team directly.
Contact Apple for help with Apple ID account security - Apple Support
I actually created a completely new Apple ID using the desired email but I deleted the ID shortly after, when I realised I could just simply change it in the settings. Maybe somehow it hasn’t realised it’s deletion? Plus I tried logging in to the Apple ID of the email I want to use and it says it doesn’t exist, which is what I expected. So surely no one else is using it?
No, but when you created a completely new Apple ID with that email address, Apple ID's don't die, so in reality it is being used by another user. Unfortunately, that user is indeed you. I'd recommend you speak with Apple Support. I don't know if they'd be willing to delete the Apple ID you created with that email address or not, but they're the ones to ask.
Since you created an ID using that email address, it's undoubtedly been 'locked'. Since the ability to delete Apple IDs is relatively new, I have no idea how long it would take for the email address to become 'usable' with another ID, if ever.
Contact Apple.
“Email used by another Apple ID”