Let’s keep the discussion focused on the fact that the shirts are safely in the topic starter’s possession and that they’re content! It’s been resolved, so let’s celebrate that!

What size did your grandson end up obtaining? It's great that you got it sorted out. Well done for not complaining. Many other people would have made quite a mess of this experience, and although I feel there's room for annoyance, I don't think it should result in anything more than pointing out the mistake. That's the best way to learn.

Not exactly fortunate, but it would have been worse if they had sold out all the shirts and none were left, as you would then be compelled to await new stock or receive a refund. Kudos for handling the situation adeptly, @Fan of Big Tone.