Online order

I am not happy with your service recently, on the 31st I bought items on promotion it was 4 items for 50%, ordered online paid but the system did not generate the order. Payment went through and I was given options to either refund or re-order and I chose to re-order, now I'm being told that the items are out of stock only 2 available meaning its no longer 50%. I am very disappointed that I paid for the items then later be told they are out of stock and there's nothing they can do, now I can't have items that I bought due to your system. ??Sad