You can contact 343i through either the Halowaypoint.com forums or you could try to shoot a tweet at Josh Holmes or Frankie for a more direct answer if they decide to answer.
I've tried Googling your issue and came up with this snippet:
HALO 5 PRE-ORDER BONUSES NOT DISPLAYED IN THE GAME
In case you have some pre-order bonuses not displayed in the game, whichever they are based on the version of the game you bought, follow these steps to see if something changes:
1. Go to Games and Apps. 2. With the cursor over Halo 5, press Start. 3. Choose Manage Game. 4. Install the Promotional REQ Pack. 5. Restart the console. 6. Start the game. 7. Go to Spartan Hub (press Start). 8. Click Requisition, then Open Packs. 9. Go to Customization and get your pre-order items
You might've already tried this, but you never know.