Changing Account users

I have paid for 3 accounts. One is working fine, one is deactivated, but even as Admin it won't let me reactivate it and one is linked to a person who has left and I need to change the name and email. I can do this however it sends an email to the past owner of the email address, the email account no longer exists! What can I do, as I need all three account to book meetings on, I'm paying for 3 but can only use one??

Thanks