Now that I reread the OP, I presume that when he says "on a first class ticket" he means that he paid for Y and was rebooked on the Y ticket but into F by the DAY agent.

If those are the facts and OP is reporting word-for-word what the ORD agent and supervisor said (did the agent really say: "there is no way you are flying First Class when you only paid $180....."), the ORD agent was rude, but likely correct. OP ought to have been confirmed onto the 10:40 and waitlisted in Y on the 9:00 AM. If seats cleared on the 9:00 AM (including those eligible for UG's), OP might have made the 9:00 AM, but in Y.

Having said all of this, you really needed to make a decision here. The DAY agent did you a major solid by forcing the F seat, thus jumping over what was likely a lengthy UG list for the 9:00 AM flight (the UG list for those flights can run to 50+ people). That same agent would likely have booked you on one of the earlier frequencies if there had been space. But, he didn't. So, there was nothing to be gained by bringing the whole thing to another agent's attention. When you did, the inevitable happened.