Originally Posted by tbogart
When I called CO to inquire about the low fare guarantee they told me I had to book the flight on Expedia, fax them them a copy of the ticket and they would assess if this would qualify.
This is not the procedure. The agent is supposed to bulid the same itin at the site you mention, and validate it for you. You do not need to buy another ticket.
The LFG works, though it is time consuming. Remember these folks are co.com web support folks. The know the co.com website, but not necessarily the others, so you may have to show them how to build your itineray. For example, you may have to walk them through how to force an airline to show up on a third-party site.
I did a write-up on the LFG when I first did it:
http://www.flyertalk.com/forum/showthread.php?t=445380