Welcome to the community!
Sorry to hear your access to extended coverage might be blocked. With the roaming agreements, mobile providers allow customers from other providers access to their networks as extended coverage (Fido-EXT). However, there are some limitations to its usage (ie majority of your usage needs to be your home network). If the majority of your usage has been regularly using another provider's network (Fido-EXT), access to extended coverage would be restricted. As far as I am aware, a restriction would last 30 days (see here). However, repeatedly exceeding the limits would have lead to the service being blocked.
You should be able to use your services when your device connects to Fido/Rogers cellular towers, though. Alternatively, if you have access to Wifi and your device is supported for Wifi-calling, you might be able to continue with Fido using that feature
There are many factors which determine a phone's cellular reception. No one would be able to determine to which network your phone connects at any given location and situation. The mobile providers can only provide approximations of their coverage areas. Even knowing the locations of the cellular towers would have limitations with regards to whether a particular device receives cellular signal at a particular location. That said, you can get an idea of your area cellular towers here.
If there are Fido/Rogers cellular towers in your area, it's possible that the cellular signal from other cellular towers is simply stronger at your location. If your device is set to automatically choose the network, it might connect to the stronger signal rather than Fido/Rogers signal. If this notion is correct, you might consider manually selecting the Fido/Rogers networks.
Additionally, it's possible that Fido/Rogers have changed the bands/frequencies used at your local cellular towers. They have already decommissioned some frequencies of the 2G and '3G' networks. The remaining 2G frequency should follow in the near future.
If the Fido/Rogers cellular signal is not adequate in your area (or your device is unable to receive the available signal) , you might consider purchasing a signal booster. If you choose this route, you would need to verify the product amplifies compatible bands/frequencies.
Unfortunately, if your circumstances don't allow for adequate Fido/Rogers cellular signal, there isn't much that can be done. It's a common misunderstanding that any mobile provider will suit everyone everywhere. That simply isn't the case. If you spend a good portion of time outside of a mobile provider's coverage, perhaps that mobile provider isn't the right one for you. As previously mentioned, the majority of your usage needs to be on your home network. If you live outside of (or on the edge of) Fido/Rogers coverage, you would likely need to switch the network providing the extended coverage.
Hope this helps 😀