Pre-ordered at Gamestop, no unlimited ammo code

Hello, I pre-ordered Halo yesterday at Gamestop, and was unaware of the fact that if you pre-order, you’d get a code that gives you unlimited ammo for the campaign. My friend had told me about it, and that it would be on my receipt. He sent me a picture of his, and mine clearly doesn’t have the code on it. Would I be able to go in to get a code, or am I just outta luck? I can provide proof of purchase with a picture of my receipt if need.
Thanks in advance!

You’d likely need to talk to the GameStop you bought it from to get resolved.

You may have two receipts - it’d be on the one you got when you PICKED UP the game, not the one when you reserved your pre-order.