Since he left it late and the WB program is over, I'm afraid you're probably out of luck, but it's worth a look:

Go to Account Management, select Services, and from there he should be able to find an option that allows him to download it - if he actually managed to get it from the WB program.

I think this is the same problem I had; where added a game to my cart and the PS store bugged out and seemed to think I made a final selection, automatically removing the title from the list of games I could select.
If your brother had the same problem, he won't be able to download the game as he never actually made a "purchase" of it in the allotted time.

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@ Leungbok
I agree, I thought that trick was old hat by now ;P

Still cool though!