Hi Please help me

Hi Please help me. I place an online order from Woolworths for Juice on Saturday the 25th and I was supposed to collect it on Monday the 27th. When I place an order, I cheked availability first and the juice was in-stock. On 27th an hour before my scheduled collection time, I received a call from the to say the juice is out of stock and they cannot honor my order. I informed them that I checked availability before placing an order and I want my order. Ever since that call haven't heard from Woolworths. Pls assist as would like to receive my full order.