Sold item on shelve / Bad management

We were so excited to find the last green play house that is on special at the moment on the shelve. I was waiting for somebody to help me to go pay for it when a guy (staff) came to take it, saying that someone else paid for it. If the box was not that big, it would literally have been taken out of my hands. The person who bought it, already had a pink one in the trolley and came back for the green one. I negotiated with them and they were willing to take the other pink house that is on display. Game did not have the box or stickers for the pink house so they did not want to take it. It saddened me to explain to my two year old that he could not have the house for his birthday anymore. The manager actually pulled up his shoulders with no explanation or apology for the mishap. He had no interest in customer satisfaction. I do not complain often but have never felt this heavy hearted and bitter leaving a shop before.