Unable to change my Apple ID email address

Welcome there, hope someone could help me with it. I met a problem that I unable to change my Apple ID email address. Doesn't matter what address going to be in there, it says : "This email address is not available. Choose a different address." I used to create my Apple ID many years ago, time passed, now I got myself to the point where I'm not using my old email's at all, due to all purchases in Apple Store, I want to feel confident that my account is secured enough and stuff. Apple not answering their **** phone support, so putting my beliefs on a true community guys, thanks in advance, hope we'll get through this together.

Mike!