I am extremely disappointed with Fido.
I recently trabelled abroad and turned off my data and kept my phone on airplane mode throughout my trip and I was still charged with roaming every day when I didn't use the service. I had wifi calling enabled and I am still being charged 14 dollars each day. I called support and they didn't offer a solution that satisfied me. This is really disappointing. All the phone calls I made were using wifi calling and every time the wifi was not good, I was disconnected and had to call again. Still, Fido claimed that I used roaming. I am really disappointed with the service.
Welcome to the community!
Sorry to hear you've received unexpected charges on your bill. I understand you had disabled data and Airplane mode was enabled on your phone. However, to clarify, was all of your Wifi-calling usage to Canadian phone numbers?
Are you aware that some Wifi-calling usage is considered roaming when used abroad (see above link). If your usage included calls and/or messages to non-Canadian phone numbers, that would likely be the reason for the roaming charges.
Hope this helps 😀