@Mcgyver do you have access to another phone that you can use to test and see if it does the samething. Also try doing a manual network search and then choose the Fido network. This way you can force it to stay off the extended network.
We appreciate the fact that you stuck by us for all these years, and we'd really hate to see you go over this.
Having reliable cell coverage is super important. For this reason, we offer extended coverage in areas where the Fido network is not available. The extended network is to be used occasionally though, and the majority of your usage does have to be done on the Fido network. If you live in an area that is only covered by Extended coverage, then this may explain why our customer service team was unable to help further. You can read more about extended coverage here.
That said, I can take a second look at your account. I'm sending you a PM so we can check things out together
Have been with Fido for 5+ years. Approx 3 months ago phone started to connect to fido-ext at my home, very poor fido signal... Bought a booster for in the house $$$
Before your phone started connecting to Fido-EXT, do you recollect to which Fido network your phone was connecting? Was it the GSM or 2G network? Rogers has been reducing their 2G networks with a view to decommission the entire GSM network in the near future (see here).
If you were connecting to the other networks, it's also possible that there is increased interference between the cellular towers and your locations (ie new buildings). The nature of mobile phones is that they are dependent on cellular signals reaching the phones. Many factors can affect those signals from reaching the phones-- including proximity to cellular towers and interference caused by obstructions between the cellular and the device (see here). That is why no mobile provider will be able guarantee their service. You can get an idea of the location(s) of your surrounding towers here.
Did the signal booster help with your reception at home? Does your signal booster amplify all of the bands/frequencies for the different networks or only some of them? That is, if your area only has the GSM network and your signal booster only amplifies UMTS bands/frequencies, it would not have helped increase signal to your home.
What phone are you using? It's possible a different phone might have better reception. It's not uncommon for different phone models to have differences in cellular reception. For example, a professor at Denmark's Aalborg University tested the performance of various mobile phone antennae (see here). I'm not sure how much we can extrapolate from his data because Fido/Rogers uses mostly different bands/frequencies. However, it does illustrate the large differences between phone models.
Unfortunately, if you were connecting to the soon-to-be decommissioned GSM network or if your signal has been decreased by interference, there is not much Fido/Rogers will be able to do to restore your signal. You could get a Wifi-calling compatible device, or you might have to consider switching carriers.
Hope this helps