Used this site for the first time last night.
I left it overnight and when I came on it hadnt worked, so I contacted the customer online chat, they we're very helpful and I had not realised I needed to reply to a confirmation email. Weirdly they kept (via email and Online chat) on asking me if they could call me, I didn't mind but they never actually did.
One I replied to the email again with my Toon/Gamertag , Phone number & AH mount description, they made the purchase within 15mins.
Very good, will likely use again (hopefully I will not spend anymore on the game though).