Bad service

I ordered a microwave online on Black Friday - payment was done and received the order receipt. I went to collect the microwave after two days in a Carnival store and I was told that I can't collect it as I do not have the invoice or they don't have one for the online purchase. The manager said to me that it takes 24 to 48 hrs for the sale to go through and receive the invoice. So, I asked him that why was I not notified to say that I can only collect it when the invoice is issued. And, why should I wait for so long after I had done the payment already. This is really disapppointing as I went all the way to collect the item and I was sent back empty handed for stupid reason. What a waste of my time and petrol!!!