Edgars cancels order after payment of items at very low price and now its out of stock.

I placed an order at Edgars online. i wanted to order 4 items where the system told me one item that i wanted 2 of is out of stock so i ordered the other 2 items and paid for the order. I received my invoice. when i logged on to my profile again a week later to see when my order will be at the shop for collection, the order said cancelled. No the tell me they are out of stock but i was able to place the order. The Addidas pants was R199 each and I ordered 2. normal price for similar pants is around R699. Very strange that I could place an order for stock that did not mention that it is out of stock and now suddenly it is out of stock after I received my invoice. Clearly it seems like they realised the price issue and no its out of stock.