I went through the process of making my account and redeeming my code. I entered my credit card details, and my bank account was charged, but the credit card form just refreshed. Now I have no game in my purchased games list.
You need to seek support through them. There's basically nothing ZO could do about this short of giving you a free game, and just... man, noone does that these days.
EDIT WEll, to make sure I am not accidentally lying... this is your first purchase of the game, right? And you were buying it from this BT store? Or are we talking about a problem you're having after setting up your subscription plan?