Extremely disappointing service

Good Day my family and I decided to go for a late dinner at Spur in GrandWest, we arrived at 10pm and we waited to be seated for plus minus 10 minutes, a waiter came up to us and stated they were closed even though their sign says that business hours were till 10:30pm the manager on duty then told us that they were out of stock of too many items to stay open. We asked if we could stay for drinks and the manager looked and could not even give me an answer, I work in the hospitality industry and in my point of view it looks like they wanted to catch an early night and purely just turn away customers. I find it unacceptable that we were turned away during operational hours. Please may I have a follow up on this matter as I am highly disappointed