I would like to buy upgrade keys for World of Warcraft Burning Crusade and Wrath of the Lich king, as I already have the client and prefer not to order the retail box. I already know that similar upgrade facility is offered in the Account Management page, however upgrade fails for some reason about which I contacted the billing department with no response so far. So I am looking into the alternative of buying CD key from third party websites, So far I found these website that offer instant delivery of the game by emailing CD-key instead of shipping the box.
For those who tried it, are these sites reliable? If anyone knows other website please share. Also I am particularly interested in the collector edition of the Burning Crusade so if someone knows a site that sells CD-key for it too list it as well
Thanks in advance