One time I ordered Tesco for between 5 and 7pm, I rang at 6.55 to find out if maybe they had already come but I hadn't heard them knock, and they told me that there was still 5 minutes to go in the slot so I was ringing up too early.
At 7.20 they left a voicemail to say the delivery had been CANCELLED because of a problem on the A12 (which had apparently been blocked ALL DAY), but they hadn't bothered to let anybody know.
I found out what store was delivering (or supposed to), spoke to the delivery manager, and he said that he would personally deliver himself at the end of his shift but that it would be around 10.
At 8.55 the shopping turned up.
I did vow never to use Tesco again, so did try Ocado, but found I was spending about an extra £100 a week with them.
Haven't tried Sainsburys, and ASDA has only just started delivering here, so Tesco it is...