Hello Wangdawei117,
Welcome to the community!
Sorry to hear you've incurred unexpected roaming charges. However, you should note that disabling data and roaming data does not prevent roaming for voice and messaging. In addition, some manufacturers might allow some data usage to occur despite those settings (see here). It is generally recommended to enable Airplane and/or Flight modes to prevent unintended roaming usage. You could then enable Wifi when required. Had you enabled Airplane or Flight mode on your device?
If you had used Wifi-calling, you should note some usage is considered roaming. There seems to be some misunderstanding regarding Wifi-calling . I'm not sure how people have gotten the impression that Wifi-calling does not use the networks. However, that is not true. While the calls and messages do not transmit via cellular towers, they still use the networks via the internet gateway (see image here). The cellular towers and Wifi are merely alternate means of accessing the networks. Calls and messages would not be able to complete or get sent/received without the networks. As such, using Wifi-calling is technically using Fido services. However, they have allowed certain usage to be free from additional charges. All the messages and calls you receive (from anywhere in the world) will be taken from your plan's voice minutes and messaging limits. As well, all Wifi-calling messages and calls you make to a Canadian phone number while abroad won't incur long-distance or roaming charges (see link above).
You should also note this forum is community-driven and not intend as a venue for customer services. We would not have access to your account. If you would like to discuss your situation, you would need to contact customer service . In addition, they can also be contacted via Facebook, or Twitter. Those methods can be accessed via the contact page posted above.
Hope this helps 😀
Cheers
