I just got off a very frustrating 45 minute call with the Priceline.com customer service trying to cancel a reservation and receive a refund. In checking their website under the My Profile, +My Trips tab, I did not see a reservation I had made 2 days prior which led me to believe that Priceline did not complete the reservation as requested. So... I booked another seat on the same airline and using the exact itinerary, meaning that I now held two seats on all of the flights. By the way, I used Expedia which I've never had a problem with and who gave me the exact same pricing as Priceline.com. When after talking with the front line CS representative I figured out I was going nowhere in this, I escalated to the Supervisor who besides telling me that I was a liar, tried to show me where my itinerary was located on their website, which after telling him 4 different times that it was not there, he basically told me that he couldn't help me and hung up on me, leaving me holding the double booking on my flight and which I now have an airline deposit which I can use in the next year for future travel.
In short, if you really have to be somewhere and want proper customer handling and care, please don't use Priceline.com but instead use Expedia where you can actually find your trips on their website. Trust me, this was a $308 lesson and one that I hope you can all learn from.
My trip was not showing up in my profile on their website, so I booked it again. Big mistake.