Sorry, to get the deal you had to forward the purchase receipt to
rewards@booksonboard.com
You then get an email from them titled
Double Reward Dollars from BooksOnBoard which begins:
Thank you for your purchase.
Your Double Rewards Dollars have been credited to your account!
I thought that was the one you had already received because it also contains all the details about how to redeem your gift certificate.
The time it takes to add the extra reward dollars seemed to vary depending on how busy they were.
Also you never have $120 anywhere, it's $60 in your gift certificates area and $60 in the rewards, which is separate.