I don't know if anyone else here was having the problem, but they posted a response to why so many people were getting the "Order Not Complete" error.
http://forums.greenmangaming.com/topic/2522/
The important part:
"Because these payment issues affected many users to such an extent that they could not take up any of the 20% offers, rest assured that once we reach a resolution there will be another code created and sent out publicly in a follow-up post, available to all users on a multiple-use basis."