I suspect T-Mobile is just deeply and embarrassingly incompetent, rather than actively user hostile. Everything, including spending more money with them, often takes a phone call. Changing plans online is impossible about half the time (depending on what you're trying to do, and it doesn't fail more often for downgrading service than upgrading). They are a phone company that barely knows how to do business as a phone company; they definitely aren't a technology or internet company, as they fail remarkably on those fronts.
Correct. Former vendor, worked with their cell network crew on many occasions.
To be more fair, all the large carriers are mostly laden with corporate procedures and bureaucracy so it's hard for worker bees to make progress even if they know what's needed. T-Mo's procedures are just more broken.
Kept getting bills every month even though I had cancelled and I was supposed to be on the free for life plan of 200MB. The representative acknowledges it was their fault every time. They removed the item from the bill every time within fifteen minutes of me dialing.
Then I changed address. They might still be billing me for all I know.
If you are in the US (reasonable guess for a(n ex-)T-Mobile customer), you might want to exercise your right to pull a free credit report check and make sure it's not screwing it up.