Not sold a product but they have it in store

I was at Checkers Bryanston Center today and wanted to buy Tinkies. There were boxes of Tinkies but they didn't have the individual packs. I had to leave without one as I was told I cannot be sold a Tinkies and the manager did not want to open one of the boxes. Her name is Dineo Bodigelo.

She even went as far as lying to me saying they only sell boxes there not the individual packs. I know this is a lie as I have bought tinkies there before. Is this your rule that we must not be sold the product whereas they have it in store? Does Tinkies even know you use their product for display instead of selling it.