Your only option at this point on Xbox 360 is to purchase the DLC digitally through the Microsoft store. All physical copies of Destiny will have expired codes (even 'new'). Purchasing a physical copy off Ebay will give you the disk, but sadly, as others stated, the codes will most likely be expired. There's nothing Bungie will do to assist you as they don't replace lost/missing/expired codes, and the retailer (whoever sold it to you) can't really replace them either as they have none to give.