Asda complaint: unfair online system

I am writing regarding ASDA unfair online ordering system. When you order online, the website show items either available or not and you select whatever is in stock and place order and in your mind you have order things that you need and asda give you 10 days to collect it or delivery and then you wait for you items to arrive. But when you collect your items you find out most of items are missing and asda response is very rude and unfair that you should get whatever something available in store that day then it should allow you to collect that day instead waiting 10 days not then its saying not available.

We stop searching for same items in other places because we thought we have order it already. And due to situation now days their customer services is very bad and rude and not even allow you to register complain and hang up the phone.