US made a mistake in coding the ticket to economy. Should have been coded to F.
GA appeared brusque (inappropriate), but maybe there genuinely was nothing he could do without spending time on the phone with US to "fix" the ticket, which he didn't have at the time.
Nice that the FA's treated you well, but completely inappropriate for them to be bad-mouthing the company to a customer. They should have apologized, maybe brought you snacks and drinks, and kept their other thoughts to themselves. Maybe offered a skykit (or whatever they do these days).