Changing Account information

I need to change my email address, on my account with UK-Y, because I have changed my server.
I am going back to my old email address. When I try to change the address I get the message that somone is already is using that address. Yes me! So they don't let me change my address.
Anyone any ideas of how to go back to your orginal email address.
They say it is very important to give your current address and I'm trying But......

Could it be the original account you had?  I can't remember the user name you used, but maybe that's still active?

Yes, I think it is all original

Then you'll need to either delete that account or log in under it and change it.

I've changed the email address in the old account I think, you should be able to change your current account's email address now.