This is a bit ironic, but I was actually supposed to fly on United on June 20th. That day I was flying from Chicago to Los Angeles. That day there were awful thunderstorms in Chicago, the kind the ground planes. Chicago being a United hub can really screw up the entire country. In fact it's pretty well known in the midwest that if O'Hare gets backed in the entire country gets screwed. My flight at first was going to be 3 hours late then cancelled all together. I had to fly out the next day. It's possible that if the OP saw seats online they were being assigned to another flight. The airlines that day WERE A MESS and probably for a couple of days after. (And no I do not work for an airline!)
I'm not going to get into her use of language, etc...