MISLEADING ADVERTISING

So I downloaded the SPAR2U App, mind you it was my first time doing online shopping for snacks and cold drinks. One of their special offers was the POWERADE SPORT DRINKS which went for R13,49 for 6x500ml. Obviously I saw a bargain and I added x5 packs plus the Nestle KitKat 180g which went for R34.99. I paid and my order was accepted. This morning I received an email notifying me that my order is en route delivery, however it was just the KitKat bars that were to be delivered and now miraculously the Powerade drinks are “OUT OF STOCK”. Why was the full order accepted for payment and processing if the product was out of stock. I don’t have the products and nobody is saying anything about my refund. The only thing that makes sense here is that someone messed up on the pricing and now the customer is inconvenienced. All I want is the products that I paid for!!!