Not honoring online order

Yesterday 1August Woolworths had a sale online with 1.5litre milk cartons. The price was so good and with out economy now I decided to buy a few boxes, I add items to my cart which show in stock I select a date to deliver and check out and pay. This morning around 8 I call the online team because my order still shows processing and I selected adelivery time between 7-9am. Eventually after 9 I get to speak to the store who's supposed to deliver my order which customer care team gave me the number to call myself as they were not getting through to be told this was a bad Marketing sale as the item is reduced to clear and they won't get stock of it again. The online customer service rep tells me we should cancel it because she doesn't think I'll get my milk because even she ordered and it was canceled and quite frankly they don't have any more ***s that's going to produce the milk for the 1.5l box milk.

This is terrible and unacceptable that you now just expect the customer to be happy and satisfied that they will now no longer get the order they placed.

Please show me a policy where this shows clearly where when you buy an item Listed in stock on your web page check out and pay whether it's a hold on the account or not that you have no further liability or due diligence towards the paying customer.