We took delivery of our Christmas order from ASDA today (Weds). There were 8 substitutions, just different size packs, and no 'out of stock' items. They notified us of the changes by email before they delivered. We had ordered a large turkey crown but they only had a medium one, but the gammon joint they sent was larger than we ordered, so it balances out, there'll be enough to go round. They delivered right on time, the driver was very cheery in his Santa hat and helped to unload the crates for us.
If your order is being picked from your local store there's always a risk that items in high demand will have sold out on the shop floor before they pick your order.
Tomorrow our bakery & dairy order will come from a local bakery, they bake to order so we know we'll get what we asked for. They even deliver on Christmas Day up to midday! Our village shop will also be open Christmas morning for those forgotten items. Last year customers were offered a mince pie and fruit punch to the strains of carols playing in the background!