Forced into paying International plan. (Edited per community guidelines) waiting to happen

I live between 2 countries and I was forced to get an international plan even though I don’t need it. I have two cell phones, one for each country so I DONT need an international plan. As soon as I arrived in Colombia I switched of my cell data on my US phone and got home and immediately connected it to my home Wi-Fi. The only use I gave it was through whatts app using my home Wi-Fi. 2 weeks into my stay I get a bill for over 600 dollars from Att. I called  for days each time spending at least an hour waiting and they kept saying the only way to reverse the bill was if I got an international plan. I finally caved due to exhaustion and had to pay 80 dollars I never authorized. This is how it works. Att hijacks your phone while abroad. Even though cell data is off they have something called ATT Wi-Fi which I never asked for. What they claim is that when my home Wi-Fi is weak , the ATT Wi-Fi takes over and charges you astronomical prices. I tried turning the ATT Wi-Fi off a couple of times but it does not let you. It is imposible to do. I do not believe my home Wi-Fi was ever weak but it randomly switched to the ATT Wi-Fi and charged these really high prices so they can trick you into getting an international plan. The only way out of this outrageous abuse of power is to suspend services the moment you land abroad. You can then have your cell phone back in your control, connector to local Wi-Fi and you are good to go. ATT needs to stay in their lane and not trick you in this manner. Its a (Edited per community guidelines) waiting to happen. Since I disconnected services my US phone has been working really well on my local Wi-Fi.