Discount code snafu

I bought the Monster Manual two weeks ago with the NOTTHROWINGAWAY code. I didn't know that the code could only be claimed once. I wanted to buy two more books yesterday at which point I figured out that the code was no longer valid. As I understood from others, if I would have bought all books at the same time, the discount would have been applied to all books. Is there something that can be done about this, so that I can buy the other books with a discount as well? 

Contact support from the link at the bottom of the page.

Thanks, missed that link, thought this was it :). Submitted a ticket now.