Bad Companies - Toys'R'Us
In July 2007, I tried to take advantage of a 75%-off sale at Toys'R'Us to buy an expensive board game (Twilight Imperium, retails for $80). Not only did they not honor the order, but they held up my money for several weeks, lied to me about the order and my money several times, and strung me along with promises that I would get my game later.
Unless this is resolved, I will not be purchasing anything from any Toys'R'Us store again.
Some details are mirrored in this thread on Board Game Geek.