We just got screwed over by Porter with this. My wife and I and a third person travelling out West this summer. Had not booked our return tickets yet. Wife and I received an email about tickets on sale from Porter. We told our friend who immediately booked one ticket and got the discounted rate, but when my wife and I logged in within 5 minutes of that, the price doubled, thanks to our friend booking their ticket, and was much more than even the regular price.