First and last time flying Air Canada. Flight up to Montreal - no hot water for tea or coffee. Entertainment screen was not functioning -the FA said "go find another seat". It was a fully booked flight. There was not room in overhead and my 6'2" son had to put his suitcase carryon under his feet along with many others. The flight attendants did not offer any help at all and were rude. Coming back was not better. I had a filthy stained tray table that was not cleaned. Boarding was delayed as the gate was switched and the Air Canada representative was extremely rude to multiple passenger over confusion with the gate change number and her announcement that the flight at the same gate number was cancelled.The lack of courtesy was unacceptable. Bad experience all around both ways.