Most of these situations seem excruciating because these droids are trained to exploit the tendency of most people to be polite and non-confrontational to the point of acting against their own needs and thus doing whatever the company wants.
Don't fall for it. State what you want, once. After that, tell them you're gonna shove the cable modem up their ass sideways and piss on their grandma's grave. Make THEM want to get off the phone with YOU, and make it obvious that the only way that happens is for them to do what YOU want, not the other way around.
Being nice is often a sure way to get hosed.