Welcome to the community!
Did you lose your phone as well? If you did, have you reported it as stolen? You can do so via My Account --> Usage & Services --> Mobile. From there, you can select Report lost or stolen device (near bottom of page under Quick Actions). If you didn't lose your phone, did someone remove the SIM?
If you are still in possesssion of both your phone and SIM, you might be a victim of fraud. You would need to contact customer service so they can investigate your situation. Alternatively, you might consider sending @FidoSolutions a PM. Once they verify some information, they will also be able to access your account. In addition, they can also be contacted via Live Chat, Facebook, or Twitter. Those methods can be accessed via the contact page posted above.
Hope this helps 😀