Selling stock they dont have

Friday Makro had their Black Friday sale. On the website it said they had 700 units in stock. I jumped online and ordered mine thinking I was going to collect it on Saturday morning. Big mistake !! Today is Monday lunch time and apparently my order still is not available for collection because they dont have stock. How can you sell something you dont have ?! The website clearly said they had 700+ plus in stock. If I had taken the time off work on Friday they would have wasted my time because I would have arrived there and they would have had no stock. What is the point of having a Black Friday sale if you dont have stock ??!! What is the point of having an online sale system when you dont have stock and then you blatantly lie to customers. Well thats the last time Makro ever sees me again.