Terrible Customer Service

I just cannot believe that their system will allow you to place on online order and payment will go through without a hitch then 3 weeks later you receive a call from them and they just basically tell you "sorry we don't have stock, you have to cancel your order". If a big store like Makro knew that they have a limited amount of stock of a particular item then it should block you from placing the order there and then! Or better still provide your customer with an alternative like another product, etc instead of just asking them to cancel! I am just so dumbfounded that a big store as such can behave like that!!!!!