Account Compromised and Authenticator Placed

My main account has been compromised. I cannot post here from that account because the account is forum-banned.

It started last night with my password being changed. When that happened I changed it to a new password, but again it was compromised and on top of that an authenticator has been placed on it, so I cannot even change my password anymore.

I've sent a similar e-mail to Account/Billing, but haven't received anything yet. Not sure what to do next so I'm looking for some help here.

Thanks.