My account is getting hacked and I feel I have no power to stop it.?

I've changed my security questions, but once prompted by the hacker, there is a link that says, "these aren't my questions." So, my old questions reappear. This defeats the purpose if my hacker knows my answers. They've even gone in to start deleting my e-mail contacts & phone number. I went back and forth with this person changing my pword back. So, I tried deleting my account. However, if someone tried accessing it again, there is a link that says reactivate. Again, this defeats the purpose. I feel very helpless right now. PLEASE HELP ME!