Cancelled orders

I placed an order on the Makro Stores Online platform for a few items, payment was nade and my order confirmed. The following day I receive an email that part of my order was cancelled, "out of stock" stated next to the items and that I will be refunded in 2-10 day. How is the order confirmed if stock availability has not been verified. This is such an inconvenience because I now have to wait 2-10 to be refunded then go elsewhere to purchase the items I need right now, I would have gone elsewhere to make these purchase in the first place had I known that they were out of stock. This is such total inconvenience, I am very disappointed.