I use Sainsburys home delivery service and am very happy with it. I have been using it for more than ten years and it was very good throughout Covid too. It’s very rare that I get substitutions and generally are ok and they take them back no questions asked. I generally buy foods to make meals from scratch, don’t buy a lot of ready meals etc.
if I’m not happy about something, very occasionally the bread is squashed, then they refund me the money but leave me the item.
yesterday I had accidentally asked for two of the same thing on my order and they took back and refunded the second.
I had a good look round the supermarkets price wise about a month ago and did think about shopping here and there but in the end decided that although something’s are cheaper elsewhere on the whole I think for quality, ie Aldi fruit and veg doesn’t last as long as Sainsburys I think Sainsburys are reasonably good value for money.
I do make use of the not having substitutions, you can do it by item, for things that a substitute would not probably be ok but that’s due to food allergies.
Ive used a variety of delivery slots but went for the home delivery service (paid for the year, runs out next August ), midweek service, but possibly wished I hadn’t as I didn’t realise it was only Tue -Thursday, I’m WFH so it not an issue it’s just that I sometimes want a Mon or a Fri, and if I do I have to pay for the delivery. I used to get £1 slots but they went up and up and that’s what made me decide to pay for it and I think by next August it will have made sense to do so but doesn’t quite suit me (you get what you pay for I suppose).