This happened to me Wednesday night. You don't need a new SIM but it's okay if you already ordered one - you can get the Mods to reinstate the one in your phone and cancel the one that was just used by the other person. But do as previously mentioned - suspend your service by marking your phone as lost/stolen. Immediately change your password and security questions - make sure they're unique and you're not using them anywhere else. They used my number to get text message verification codes sent to them so they could access my other accounts (with the same email address) by resetting my passwords. They accessed my PayPal and made fraudulent charges. If you have a PayPal account linked to that number, check it to see if there are any charges you didn't make. I canceled my credit card and it stopped them from making any more charges. Assuming you use that email on other accounts, go through them and change the passwords, especially for the ones that have the same password as the one you use for your Public account. Major ones linked to your financials would be the first place to start. If you got a ton of spam emails (as I did - a diversion tactic), go through those and see if there are any password reset ones. Make sure you go through those and change them. Go to the website directly from a browser. Don't click on any links in the emails - those could be fake.
For the ticket you submitted - was it submitted as a security issue? They might take longer to get back to you if not - it took a few hours before I got a response. Use SIMon, type in SIM hijacking. That will helop create a ticket noted as a security problem. They might answer those faster than regular tickets. Also, email privacy@publicmobile.ca and tell them what happened. Leave another phone number where you can be reached if you haven't been able to re-gain control of your phone number yet.
