When I had a similar issue some time back they contacted us, apologised, offered a delivery the next day and can us £10 compensation. If I have ever had to contact their help line they have been extremely professional and helpful. I've been with them years and have been impressed with the service.
Once when we were both ill and I did an online order and wondered why it hadn't come and rang up found that I had clicked the click and connect button instead of home delivery. They explained my mistake and said they could give me a home delivery slot the next afternoon. Unfortunately, because we have no one to help us we had literally run out of all essentials. The help desk said they would ring me back, 10 minutes later they said they had phoned the ma ager of my local store and explained my situation. He had said if I felt well enough to drive they would reopen the click and collect, which had been closed for 2 hours. When I got there there were two members of staff waiting who wouldn't even let me get out of the car but carefully put my groceries in the boot and back seat. Wished me and my husband a speedy recovery and were all smiles. What more can I say.x