Tastes like pond scum

Just got to my office. Took a sip of the Dunkin’ Donuts medium coffee with cream I bought on my way out of the subway… BLECH! Tastes burnt and like there’s a faint flavor of something to it as if the urn was never rinsed out properly. They charge me $1.70 and they can’t even deliver a decent cup of Joe! Do I just throw it out or march back there and demand a better cup of coffee? I really need coffee right now. I feel I am trapped in a bowl of jello. Darn this situation! I am angry!