Koodo needs a simple setting in self serve to protect against extra charges. It should block all pay per use charges, like premium numbers, international roaming, international calls if not included, data that's not included, directory service, etc.
That would make it easier to get phones for children, seniors, employees/contractors, visitors, etc.
While prepaid may help in some cases, not all services are available with prepaid, such as the voicemail to text add-on, or international call add-ons.