I stopped booking on these third-party sites when they charged me a cancellation fee on a full-fare ticket. Specifically, three years ago I booked a domestic China tickets with Air China via Expedia. Because it was a last-minute purchase, the ticket was booked into the Y fare class, which on Air China can be cancelled free of charge. One day before departure, I needed to cancel it, only to learn that I need to pay $50. I argued that this ticket can be cancelled without penalty under Air China rules, but was told by Expedia that THEY imposed a minimum of $50 cancellation fee! Oh, well