Takealot cancelled my order with no attempt at fulfilling it

I placed an order of five items today. I have now received an email from Takealot that one of the items, a cell phone cover and pop socket combo for my wife, has been cancelled and my account credited for that item. Now, how was I able to order something today and, on the same day, it is suddenly not available? That makes no sense to me. This is Takealot's error, yet I am being punished. My wife wants that particular item, so how does a credit help if Takealot now claims not to have it? Also, our order was over R450 so we are getting free delivery. Now, if we tried to order a replacement item, we'd have to pay for delivery. Is that the way to treat the customer?

In conclusion, Takealot committed to deliver an item that has been paid for so it's their responsibility to fulfil the order and deliver all items purchased. A credit will not help me. I need Takealot to source and deliver every item I ordered today.