Delivery time just an empty promise!

I made an online purchase on 15 December 2018 from Woolworths on line and on 17 december i received an email that my item would be delivered between 20 & 24 Dec but to this day no delivery. on the contrary an online purchase made on 17 Dec from Edcon was delivered on 19 Dec. Why is Woolworths delivery taking so long after the promised date.