I received a new T3200M modem yesterday. It installed correctly and both the Ethernet and Wifi were working with the default settings.
I wanted to change it, but it wouldn't let me log in as admin. I phoned tech support and together we did all the same stuff that I did myself, with the same result. When we switched from Google Chrome browser to Fifrefox, we finally wer able to log in and make the changes I wanted to make (change SSID and Wifi password).
I'm pretty sure the issue is that Chrome requires the https protocol, while Firefox can still use the http protocol.
Sorry you had to go through that experience and glad you were able to change your SSID with our agent.
One thing you can try is downloading the My Wi-Fi app. If you have a T3200M modem, you can log into to the app with your My TELUS credential and you can edit your SSID/password as well as your guest SSID!