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Sorry for the necropost but no one seemed to have answered the question for OP. I broke the cupholder like OP's where the flap was facing up, all you have to do is try to pop the two sides back into position putting pressure near the edge on where the joints are. Hope this helps someone googling the question in the future.
When I got my G from the dealer I noticed it was missing n I swear the sales guy went to the back n came back out with that peice n simple popped it in, if I was you I would simply try to find a totaled out G n grab it for like 5 buck, pretty sure you can find something. Good luck.