Why is there one thread on this topic? I read as much as I could follow of the original thread, and as nearly as I can tell, OP bought a ticket from Expedia involving a codeshare between UA and AC, there was a schedule change, and Expedia failed to do its job as a travel agent and reissue an updated ticket. By the time OP got to.. whosever.. counter, the flight was full and they were delayed a day (AC put them on the flight the next day). OP has chosen to interpret this good customer service as an admission of guilt (file under "No good deed goes unpunished.")

It's not clear to me what damages OP thinks have been suffered that would warrant a court action, but whatever they are, they're Expedia's responsibility, as they served as the travel agent for the transaction. That's what a TA does -- handle details like this for passengers who don't want to sweat the minutiae themselves.