False 1.5L milk advertising

I just received a call from Vusi from Woolworth Albarton lemontree telling me that their out of stock,I ordered yesterday in the morning only to receive a call at 10:30 and my collection time was 10:00 to 11:00. How can they be out of stock while when I ordered and payed stock was available,I want my milk not refund. Order number O***