We were making our way to Prague from Houston for a river cruise vacation. Working with United Airlines, we chose the option that fit our time schedule best, which was to fly through Toronto and use Air Canada for the leg between Toronto and Prague. Prior to the flight, I found Air Canada difficult to contact and work with when scheduling an upgrade to our economy booking but the onboard flight treatment of passengers and service was even worse. In the future, we will do our best to avoid flying Air Canada. Our return flight from Prague to Houston through Frankfurt on Lufthansa was much better.