They were talking about it being hard/easy to leave, which seemed like a single data point. I'm on T-Mobile, and I like them, and I'm not surprised to hear that they have good support for leaving. But I still have had at least one experience where I had to furiously remove myself from their store over some bs they pulled. Should I now boycott them? I'm not even talking about the principle of second chances, but just that I'd run out of providers real quick if I had to boycott them for every one or two offences, as much as maybe I'd like to.

There's dozens of mobile providers. What kind of "bs" are they pulling that you'd want to boycott them all? I had several in the US, and all the smaller ones (MVNOs) were fine: they did exactly what they claimed as far as billing and level of service. The only reason I left any of them was because I found better network coverage, or moved. I honestly don't understand why you'd want to support a company that treats you poorly when you have SO many alternatives.