False advertising by shoprite

Recently shoprite had a promotion of almost 50% off on a number of items and the promo was supposed to run for 4 days, my interest was to buy omo washing powder which was R49ea for 2kg but guess what, in less than 2days I couldn't get omo at shoprite Pritchard st in joburg, first I sent my kid and he came back empty handed and then when I was off I went there myself and still there was no omo, when I tried to do a raincheck I couldn't either because I was told by this controller that I can't, so why false advertise things that you can't provide because when you put up a promo like that you must have enough stock to last upto the days stipulated, I'm so disappointed in shoprite and I call that lack of customer service and false advertising.