Disappointed In Online Shopping Service

So I decided to use the Dischem online platform to order some much needed essentials. Was later called to be told that certain items that I had ordered are out of stock and that I'll be refunded for them. I feel like this is *********** as the items should've been marked "out of stock" on the online platform instead of allowing me to order them. When I took this up with them, they sent me an email telling me that items are advertised as what they have in the front shop and that they might run out by the time an order is processed. My question is, if something is available and ordered, should it not be set aside to avoid such situations? I'm pregnant and could be giving birth any time soon but I'm still awaiting my order. The order was made on the 7th of this month and 5 days later, still nothing. I'm truly disappointed in the service they have provided and how they are handling everything.