Canceled item when there's clearly stock!

Good day

So I've signed up to takealot and takealot more. I made a purchase of 2 items. Yesterday I received an email that they're unable to deliver my 2nd item because its out of stock when clearly the item is still in stock and im able to add it to my cart today.

I'm writing this to complain that my first time buyer discount went to waste and I feel this is *********. I do not wish to support such a business.