How to contact Apple if somebody has created an AppleID using an email address of mine.
How to contact Apple if somebody has created an AppleID using an email address of mine.


This particular answer is meant to address the qualifier (emphasized)  portion of the question.

Unless your email address is not 100% solely in your control, this cannot happen.

Why? Because immediately upon creating an AppleID, you are immediately asked to confirm the account and an email is with with a code only; there are no links to click or addresses to reply to.




To be perfectly clear, an AppleID cannot be created unless someone physically types out the confirmation code in the boxes on Apple's AppleID website.

What this means

If "someone", whether nefarious or innocent intentions, created an AppleID account with your email address they either had:


access your email account
access to a trusted device that's no longer in your possession (sold, gifted, or stolen) 
you confirmed the account and forgot about it.


What is Apple going to do?

Nothing, unless you can authenticate with the credentials the account creator provided.  


email address
Birthday
Phone Number (required in some countries)
3 different security questions with 6 options each as to the question being asked (18 different permutations)


Apple needs to validate who you are before it will even contemplate making a change.  The reason for the extra verification credentials is for the simple reason email addresses and phone numbers change; your birthday and the city where your parents met (one of the questions) will not.


  So far as I know my account has been hijacked. I say my account, because it's my e-mail address which is used to login. So far as I know this is some variant of a malicious social engineering attack.


It could be your account and equally as likely it's not.   We (here on Ask Different) and Apple only have your word that the email is in fact "yours."  How do we know that you haven't compromised the legitimate AppleID account owner and you're attempting to hack their credentials? How secure would AppleID be if they allowed anyone to merely claim an email address was theirs and to reset the password?

(It's not an accusation, it's an academic exercise)

I can already hear your argument:  It's my email account.  Ok, let's look at it from Apple's prospective:


Given the security process, your email must have been compromised when it was created
Given that you can't authenticate any other security credential, but claiming you've got access to email means email is potentially compromised now.


From Apple's perspective, it's not their problem.