Extremely disappointed in online shopping processes

Extremely disappointed. I ordered products which I desperately needed on the 5th and 6th respectively. DisChem sent messages confirming that the orders are being processed. Delivery should take 3-6 business days. On the 3rd business day of my first order I get a call to say the store does not have stock and they need to refund certain products. I do jot understand how the order is allocated to a store that does not have the products I ordered in stock. Furthermore, if this is your process, why not contact me on the first business day so that I can make alternative arrangements for the products I desperately need. It is now Friday afternoon 16:50. Your call centre is closed and I will not be able to make alternative arrangements until Monday...and wait another 3-6 business days before I get a response. Do not offer online shopping if your processes cannot cater for it!