Charged for OUT OF STOCK items with 2 week wait for refund?

I ordered a few essential items through the Pick n Pay Bottles App. I went through the process of selecting an alternative for one of the items that were marked as 'out of stock' while the shopper was selecting my items. All the items I selected to purchase was 'picked' and 'charged' to my card. Much to my surprise when my delivery arrived, 11 (eleven) items were missing from my order.

I immediately contacted the Pick n Pay Call Centre to report the missing items. I was promptly informed that the store did not have stock of the items and that it was the reason I did not receive the 11 items.

I am perplexed at this response, as I would like to know why I was charged for items that were 'out of stock'?

The support team then processed a refund, only for me to accept the waiting period of 3-10 working days for the refund. But wait, then I realise, upon receiving the refund email, that not all the items missing from my order had not been refunded.

Again I sent a query, informing the support team that my refund was processed incorrectly, only to be told that a refund was processed already. I agent obviously did not read the query and sent an ill-informed response.

I find this utterly appalling and find the fact that a patron is charged for 'out of stock' items and then has to wait a maximum of 10 working days for a refund unacceptable.