One of my colleagues traveled to China on Air Canada with 4 family members, and upon checkin for the return flight with Air Canada was told they could not return on August 26 because there were no seats. He was finally able to return Sept 4, and some of his family are returning on Sept 8. His invoice from the travel agent indicates their return booking was August 26, but Air Canada says they had no record of his return. Air Canada told him he needed to check every day with them to get a seat, which he did, but to no avail. He finally obtained a seat when he told the agent he was going to protest in front of the Air Canada ticket office and perhaps be arrested in China for protesting. Before he did this, he told them he was going to go to the US embassy and tell them of his plans.

How can something like this happen? What recourse does he have?