This is a very, very important thing for people to follow. As a CSR (well...CAE, but same thing), I get to make the decision on whether or not one gets what they want. Even if the person calling is right, if they start talking down to me, or make me feel like an ass, and I'm in a bad mood - they can wind up keeping themselves from getting what they want. Asking for the supervisor usually doesn't work (in most of my call center jobs), because we talk to the supervisor first, and if I tell the sup "This person is a jerk, don't help them with anything more than you have to," the sup will only do what is absolutely necessary, and nothing more (which means that instead of a cash credit, in many instances, the customer will recieve credit toward future statements).
Oh - one more thing - no CSR cares if you're going to go to the competition. Saying "You're going to do this, or I'm going to your competition," means nothing to a CSR or a supervisor, because every CSR that likes his job believes that his company is the best, and you'll be back....it's true! Until the CSR gets disenchanted (as I have) with their job, that is the mentaility that they keep.