Ask The Consumerists: How Do You Stay Calm When You're Being Wronged?

Stacey has an interesting question for the Consumerist hive mind. She wonders: when you are in the middle of a grave consumer injustice, how do you stay calm? How do you hold on to your temper and stay professional, whether on the phone or dealing with a company in person?

I have read enumerable stories of consumers facing completely
ridiculous, unethical, and even unconscionable issues. When consumers
get upset, they are often reprimanded by the readership for not being
professional – but as a very emotional person and someone who feels
great injustices should hold the responsible party responsible, how do
I hold my temper? I’m pretty good at not taking the problem out on
the representatives on the phone, unless the person cannot or is
unwilling to solve the problem. But when the company is clearly
uninterested in the law or the right thing, how to keep from verbally
releasing your frustrations?

Any advice for Stacey?