On WiFi but using my data

[Laineeb]

So I'm at home having a Facebook call using my WiFi, and I get a message saying that I have used 75% of my data for the month, I immediately check and it's says I'm using Fido WiFi! I go on to my account to check and yep I have 27 days in my cycle but have used 70%of my data. 
I barely use 1gb/ month usually. 

Why is my I phone using up my data for a video call when I have WiFi! It did the exact same thing 2 days later and now I've used 90% of my data! What is happening?!

I don't want to turn off permission for messenger to use data because I want to get messages when out of WiFi range, but I don't want it to use data for video calls, especially when I have WiFi! Help!

[Cawtau]

Hello Laineeb,

  Welcome to the community!

  What phone are you using? Have you verified that it does not have a setting to boost connectivity? I believe Apple calls their setting Wifi-Assist.  Android devices might have similar settings but named differently.

  That said, there seems to be a known issue ?? (see here and here). Unfortunately, I'm not aware of any solution or updated information.

Hope this helps 😀

Cheers