Frustrated

Hi, today I went to Chicken Licken at 18:15 because my girlfriend and I wanted to have the rock my soul. So we got there and brought 2 and waited for about 15 mins our slip was order number 333 and order number 334 got his order before us and it was a Rock my Soul as well however they then called my order number and told me the was one rock my soul left. Felt irritated and dissapointed because we waited for nothing... 1st of all how can someone who brought after me get his order 1st and how can 1 wait for something is out of stock.