Woolies Online ''pay for 6 and receive 5'' just isn't good enough

Unbelievably bad customer service from Woolworths online. I ordered 6 items and received 5. On follow up via email (their call centre number isn't functional and doesn't allow options to be dialed, just repeats the main menu over and over), the response I received was that the 6th item was out of stock and that according to their online terms and conditions, stock of products is limited and therefore they cannot always guarantee the availability of stock. No solution, no refund, just goodbye, we were out of stock? Its laughable. At not stage post order and prior to delivery was this made known to me. I expect better. Maybe if it was the customer service administrator's money a resolution would have been forthcoming. I await further contact Woolworths Online support