Hmm, i also encountered the same issue, i read about the promo on the home page but only bought the game hours later from the shop directly not realizing that the offer and the shop is totally different, or purchase from the shop auto upgrades the edition as per the offer.
My friend has been persuading me to join him in GW2, and i finally tipped when i saw the offer. only to realize that the norm does not apply in the shop where offers are auto upgraded.
Sent in an email to support, hopefully that they can work this out