Not open on a Sunday at 17:15

We were at Sun time square on the 20th August. At our arrival at the restaurant we were very surprised to stand infront of a closed restaurant.. on a Sunday at 17:15.. on the website it clearly states that the restaurant's trading hours are 12:00 - 23:00 on Sunday's? We were very dissapointed as we travelled all the way out to Guy Fiery's restaurant to only arrive at a closed restaurant. What happened??