I encountered this issue as well. It was very similar to Sarsen.7620’s issue. I attempted to purchased Gems with gold while the Trading Post was down on Sept. 19 and received a “Failure” message. The following day I logged on to see the Trading Post was back online and my 5 gold pieces where removed from my inventory with no Gems given. I have since stopped using the gem store at all since this and probably won’t use it again until I get some type of response to my support ticket.