How can I contact a apple representative some one are using my Apple ID

You might want to consider changing your password and making sure it is a strong one. You can also add 2 Factor Authentication to your account for more security. If the attempts continue, you might want to consider a name change.

Apple ID has been compromised

Apple ID Name Change

Apple ID Password Change

What to do after you change your Apple ID or password - Apple Support     I suggest doing this before you change your Apple ID or password.