Paul, no need to even mentioned winter war patch because you have countless confirmation from the entire community. In fact, I would even challenge you to find another person just like you, who did not receive a Dragon Shirt after exalted 2. I bet you cannot. You have all the statistical relevance to build a case here.
If the NCSoft contractor customer from India or other foreign lands who never play L2 but read off scripts and copy/paste from their "knowledge database" tell you before and after winter war patch, it will just confuse the matter more for Juji.
Simply put, you did not get dragon shirt. record a video showing not in private warehouse, not in personal inventory, go to heine npc, click to exalted 1 & 2 to receive the reward and see that error message saying you have already received.
also challenge ncsoft to reproduce record of you receiving exalted 2 reward, opening it with dragon shirt populating it inside your inventory, and THEN you dragging your dragon shirt and deleting it in the trash box (which i don't think you did). but if ncsoft cannot reproduce such event, then just tell them to FIX it and GIVE you the dragon shirt and whatever else that you didn't receive. I believe every action is traceable at a developer's level. so this require @Juji assistance to get past customer support and submit a developer's level ticket for you.