In your self serve account you can suspend service under the Lost/Stolen Phone. This prevents anyone from using it. When the new sim arrives log back in and activate it under New Sim.
Good luck.
>>> ALERT: I am not a CSA. Je ne suis pas un Agent du soutien à la clientèle.
Also, as an alternative, some people on this community keep spares that they are willing to part with, if you post the general area you are in someone may respond with one for you to come pick up.
You can order a new sim card on this site, there is an Order a SIM Card button under the Getting started tab. The sim cards are free of charge and would normall be mailed out free via Canada Post, but with the impending postal strike they are being sent out by courier, with the courier charges being rebated, please see this thread for details: http://productioncommunity.publicmobile.ca/t5/Announcements/Canada-Post-Strike/m-p/57464
