Before you bad mouth an entire organization, why don't you first consider the source?
I can almost guarantee you that the representatives you spoke with at T-Mobile were hourly employees who were barely making minimum wage, and sitting at desks nowhere near their corporate office. You have to understand, the level 1 technicians at most tech support lines are merely people who applied for a job, and got a call back, with absolutely no prior company knowledge. How do I know? I see this kind of thing all the time. I'm a tech support representative for a very large electronics manufacturer.
I work with so many people who know nothing of our products, or electronics beyond the realm of the one week training they received. Which, I can assure you, is very vague.
I can assure you (and everybody) that anytime you've had to call phone support, and thought your issue was taken care of, when come to find out months later it actually wasn't. You initially dealt with a new hire who wasn't really sure what he/she was doing, simple as that. I see it happen every day.
One tech support representative that is sitting at their desk, counting the hours til they leave, willing to say whatever to whoever just to get them off the phone does not accurately represent an entire company, or their products.
And let me give you a hint, from tech support representative to caller. Getting angry on the phone does nothing. Absolutely nothing. As a tech support rep, it's a given that you will deal with no less than one completely irate customer per shift.
Here's a tip, to the original poster, and anybody that ever loses their cool while on the phone with tech support. No matter how mad you get, or how poor the customer service is, it's not the representative's fault, ever. They've been left with the bare minimum of information they need to do their jobs. A simple "I know it's not your fault." means a world of difference to us. Losing your temper will get you no where. Trust me. People that begin swearing at me or raising their voice, get the same treatment in return. Although we'd lose our jobs if we said what we really wanted to, we get our subtle revenge in ways that just make you angrier. Losing your temper does nothing. Just keep a calm tone, and all will be good.
And this, is why it's so far beyond easy for me to disregard your post.