Okay, I searched the forum and didn't find any information that fits my situation so here goes...

I have a ticket booked back to the US from Shanghai in late September with a return approximately mid-October. I would like to change the ticket to lengthen the trip. The problem comes up with the fact that I also want to see what the price change is for a GPU eligible fare (though no flights with upgrade space are available at the moment). I've set the search up with the advanced search to search for W (or WVU) fares so I can see the costs, yet I still keep getting non-upgradeable fares returned to me as results (KST).

Anyone have any ideas how to do this online or do I need to call in?