An Xbox 360 title update has just gone live for Battlefield: Bad Company 2 which will allow all players who bought Dr Pepper and used the codes to unlock SPECACT kits to obtain achievements. Any progress you have made to the achievements already will be taken into consideration so if you meet the requirements your achievements should pop when you next go online.
Players in North America that have Dr Pepper codes can still use the codes against Battlefield: Bad Company 2 on Xbox 360 to claim one or more of the four SPECACT kit upgrades. For more information check out the Dr Pepper promotion page.