Email now received, presumably because the driver told them I asked where the rest of the consignment was:

“We are sorry to advise that there has been an unexpected delay with your delivery, we are working hard to get it to you as quickly as possible, but it won't be today.

Don't worry, we will be back in touch on the morning of delivery with options to reschedule if the new date is not convenient.”

I’ll just wait at your convenience then shall I you incompetent twats? How hard is it to make sure you’ve put both boxes on the van?