This is a site that sells seats that they do not have access to.
We purchased four tickets to travel to Spain and they called us soon after to let us know that those were in fact not available and offering us other seats on the same flight, but for an extra $550 per ticket. Selling something you don't have is actually a scam, but is somehow allowed through this website. Do yourself a favor and go through one of the well-established sites and skip this one.