https://www.speakoutwireless.ca/speak/reviews/great-service-from-speak-out-stolen-phone/
and
https://www.speakoutwireless.ca/speak/phone-features/sigh-lost-my-phone-just-topped-up-100/

First, try calling the phone as many times and for as long as possible in case someone has recovered it.

If that fails (or you cannot wait any longer), call Speak Out customer service and explain the situation. To verify that you are the proper owner, they'll ask for either your 4-digit account password or a list of frequently dialed numbers. Then they'll temporarily disable the account so the lost SIM cannot be used. You'll have to go to a 7-Eleven or the online store to buy a standalone SIM card (and a replacement phone if you don't have a spare one) but DO NOT activate it. Then, call customer service back and give them the activation code for your new SIM card. In 1 business day, your phone number and outstanding balance should be applied to the new SIM and it will be ready to use.