ONLINE ORDER PAID FOR AND NEVER DELIVERED

Last week Tuesday (30th January) I placed an online order with Woolworths for the first time. When you check out you can choose your preferred Delivery slot - I thought that was so fantastic - except my order was never delivered. I have been waiting since my delivery time chosen - nothing. Not a call or email. I have emailed woolies, left several Facebook messages, I called them on Saturday and the lady I spoke to said she would get back to me.... still nothing. I don't know what more to do to get some help. I am so frustrated with the service. What is the point of choosing a delivery slot if they don't deliver? How do I get some assistance on this??