you can make a reservation for the restaurant on their website, and purchase tickets on the reunion tower's website too.
You go inside where they also have the entrance to the hotel. I myself used a tunnel under the train station that led to the main lobby where they sold tickets. For the restaurant I'm not sure how to do that.
Usually you can go to reunion Towers website and they should have an event stabbed in did she show you where to purchase tickets for events that they have
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