Hello Xiashoucheng,
Sorry to hear you've incurred unexpected roaming charges. However, you should note the forums are community-driven and not intended as a venue for customer services. We do not have access to customers' accounts nor would we know what was previously discussed.
You should also note that it is not a Fido issue. I understand your mobile data and roaming data settings were disabled. However, the mobile providers only know usage, not what settings may or may not have been enabled on a particuar device. Unfortunately, the device did log data usage.
I also understand that you may not have intended on using data. However, you should note that disabling those settings does not prevent roaming for voice and messaging. In addition, some manufacturers might allow some data usage to occur despite those settings (see here). That's why it is also generally recommended to enable Airplane and/or Flight modes in order to prevent unplanned roaming usage. You could then manually enable Wifi when required.
I am also aware some people have referenced other providers not charging for such data usage. While they may have forgiven an initial instance of such roaming data, they appear to also be charging for data usage even with those settings disabled (see here, here, and here). The issue is not limited to Fido (or Rogers).
I'm sure there are others who will claim it's a Canadian mobile provider issue. However, the issue appears to also affect our neighbours South of the border (see here and here). Their plans and roaming features may be slightly different than on this side of the border, yet people also note data roaming charges despite data settings disabled. In addition, the issue appears to also affect European Countries (see here).
@xiashoucheng wrote:
... The most likely cause is Fido incorrectly logged pin and another possible cause is network handshake...
There are numerous examples showing that this issue seemingly affects customers Worldwide. The issue is some devices are letting the data usage despite data and roaming data settings disabled. Yes, there are people who have suggested it's due to a network handshake or phones pinging the cellular towers. All mobile phones ping and conduct handshakes with cellular towers. However, the issue does not affect all cellular devices. As illustrated by this member on another forum, only some devices have this issue (see here). Apple has apparently acknowedged that their devices do allow 'SIM data' with data and roaming data settings disabled (see forum thread above). Unfortunately, no one is holding the manufacturers accountable.
I do not know what device you use. However, with the case of iPhones, I believe the issue stems from Apple and their protected ecosystem. The reason I heard a long time ago (unfortunately unable to locate reference) was that Apple devices need to connect to their servers in order to operate correctly. That connection is not a simple cellular tower handshake or ping and not related to mobile providers.
If you do not use an iPhone, it's possible the manufacturer of the device also requires similar access to outside servers. As mentioned, all devices ping cellular towers. However, only some devices need to connect to other servers as well...
Hope this helps 😀
Cheers
