Paid R100 for weekend delivery and item not delivered!!!!

I ordered 2 items using the mobile app and paid R100 for weekend delivery to arrive on Sunday. Only one of the items was delivered on the weekend and the other is on standard delivery and due to be delivered during the week (4 days later). Why did I have to pay so much? Why was the other item not delivered? Why did it not specify that only 1 item would be delivered during the checkout process on the mobile app? These items were gifts and now the one is late!!!!!!!! Absolutely terrible service