Why sell something on Black Friday, if you do not have enough stock

Why sell something if you do not have enough stock, I received sms today saying that my order has been cancelled and this is a third times this people doing this to me, why advertise something on the website whereas they know very well that they don't have a stock. their services its very poor shame. worse part i called them yesterday 11 December 2017 one of the consult said to me your order its on the way. please help my hello.peter