you're screwed bud. Bandai REFUSES to do anything about retailer preorder codes. I fought them and amazon for weeks back when next order came out. Amazon eventually refunded me $20 so I could buy the code on ebay...Amazon support just emailed me back and told me to contact Bandai instead.
Here's part of the email they sent me back then.
Thank you for contacting Bandai Namco Entertainment's Technical Support and Warranty Department.
Again, I do apologize but this anything that's retailer specific is sent directly to the retailers and we don't receive replacement codes for such products. Again, this has been escalated for investigation but that's all the information I have available regarding this at this time.