The Never Settle: Reloaded promotion has expired. There should be instructions given to you (but not on the coupon-code) to go to the Radeon Rewards Portal.
Try choosing "Never Settle Reloaded" in the drop-down. Perhaps once you submit, an e-mail will be sent to you pointing you to Radeon Rewards.
FYI, Radeon Rewards = www.amd.com/radeonrewards
AMD Customer Care
The information presented in this document is for informational purposes only and may contain technical inaccuracies, omissions and typographical errors. Links to third party sites are for convenience only, and no endorsement is implied.