When you finally do get through to an agent, you'll hear something like: "Welcome to DSL technical support, my name is Larry how can I help you today?" You give Larry your account number and begin to explain your situation, knowing all the while that this is a formality. As soon as you stop talking he'll begin the same dance you've danced every time you call tech support.
You conclude your exhaustive rundown of your case history. There's a beat, and then Larry responds, "I understand sir. Can you tell me. Is your computer plugged in?"
Reason for the Suck:
Every call Larry takes is subject to quality control which means he's being monitored. And the Big Brother in this particular situation requires he ask you if the computer is plugged in, if the power is on and if the monitor is on as well. If he gets caught doing something else he'll get fired. He doesn't necessarily think you're borderline retarded, he just has no autonomy whatsoever. Larry is like a CSI: Miami cast member: a now-soulless abomination with a script that he must follow against his better judgment.
Most tech support agents you've spoken with are sitting in a giant, cubicle-strewn mess of a room with hundreds of other agents, all at their computers with headsets on, all running the same tech support software. Most don't actually have any computer expertise. By and large they're recent high school grads, single moms or social malcontents who refuse to wear anything that doesn't feature a character from a Tim Burton children's movie on it. They're trained for 30 days on the software and are encouraged to just read along with the computer for each call. So in most cases, Larry's bosses aren't exactly wrong for discouraging any off-prompter improvising.
That's why every time you call with a different problem they ask you to do the same thing. It's not that they don't know what they're doing (though they very likely may not), it's that they only have one thing to do and this is it. It might help you feel less frustrated to think of each tech support call as a horrific fall down a set of stairs. Fight as much as you want, but there's only one way that this can go, and each step leads to banging your head.