You cannot blame Sainsbury's for this, they have a limited number of drivers and vehicles hence the lack of slots. They are doing what they can but they can't satisfy every customer, and I can guarantee every other supermarket are having the same problems
Absolutely this! ^
I've just had my S/bury delivery - pretty much everything there though a couple of items were substituted (Bourbons for custard creams - really, Sainsburys ).
However I did not have a huge shop - just the usual. I'd accidentally ordered two bags of flour instead of only one, so sent it back - someone else will make use of it, I'm sure, as flour is one of the things which is apparently flying off the shelves.
Had to send the substitute dog food back as they sent gravy and my buggers will only eat stuff in jelly (or from bins, or decaying corpses they find lying about in fields, obviously - the myx epidemic we had a few years ago was a bloody joy, I can tell you!
). Also I had ordered frozen sweetcorn and frozen green beans, and they had no beans so substituted with . . . more sweetcorn.
Other than that I'm quite pleased. I didn't order any loo roll or hand sanitiser though, so I don't know if I would have got it. My Zoflora was in stock.