Welcome to the community!
Sorry to hear of your difficulties reaching customer service from abroad. Unfortunately, you should note this forum is community-driven and not intended as a venue for customer services. We would not have access to customer accounts. If you wish to disable roaming on your account, you would need to contact customer service. I understand you are currently outside of Canada. They do offer a number which can be called from abroad. Is that number the one you tried to use? 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 😀