Pretty much this same exact situation happend a few months ago. Basically, the guy who wasn't happy with the deal (that would be you in this situation) was screwed, because there was money involved, and they had already spent it. They could not refund the other guy the money. I get that there was a PC card you needed, but jeez, people can't spend money until both sides of the trade are complete. Otherwise, stuff like this happens.
First BO Mafia Game Winner