Cancelled purchases due to no stock with no refund

I made my first online purchase MAK*** on 18/07/2023. One item was cancelled due to no stock and I still haven't received my refund for date. My 2nd purchase was MAK*** on 21/09/2023 of 3 items. I recieved and email of 2 cancelled items today due to no stock again. With every purchase I pay a delivery of R50, it wouldn't make sense to me to make such a purchase for 1 item. Why am I able to process the purchase in the 1st place when there is no stock? Will I have to wait an additional 3 months+ for a refund again?