I booked a flight with them: Toronto/Brussels. It was an emergency: I was going to visit my dying brother.
Unfortunately, upon my arrival to the airport, I was rejected because my flight wasn't booked. I called Cheapoair from the airport to learn that they decided to cancel my flight for the following reason: "The Price requested for your itinerary has changed. You have the RIGHT to cancel this booking." Which means: "We just decided to change the price of a product that you already purchased". I could not cancel due to the emergency I mentioned.
They made me pay 1,594.55 (the original price was $1252) for a flight with return from Amsterdam.
I had to pay a train ticket from Brussels to Amsterdam, and a hotel night in Amsterdam. I wrote two complaints and called them, and they never got back to me.
Review about: Cheapoair Flight Booking.