7 Jan 2016: I ordered a washing machine and the recycling of the old one. I was disappointed that a new machine was not delivered on 8th Jan., but Argos did achieve taking the old one away. Their website does not make it easy to view order status, but it became apparent that the order for the new machine was lost (while Argos retained the money). After numerous phone calls another "order" of mine was found, which was for two delivery charges of £499.96 (see photo), a bit excessive considering there was a special offer of free delivery! The help line operator admitted there was a problem, and said they will deliver in a few days. In the meantime I’ve made a note: “DO NOT USE ARGOS ONLINE, DELETE ACCOUNT”
Update 19 Jan 2016: The washing machine was delivered and works fine. However for the warranty to be valid I need an Argos sales invoice which they failed to provide. Argos customer services say contact the washing machine manufacturer. Now I'm trying to convince Argos that they should provide the sales invoice, this may take some time. The Argos website has very limited functionality, but it's possible to find an order summary if you know the order number.
Update 23 Jan 2016: I received a sales invoice by email today.