I thought at first it must be another deliver in the great Littlewoods scam, but when I picked it up I could see that it referred to the initial delivery of the TV.
Perhaps I have had my head turned by the rerun of Sherlock, but:
a. I am sure that the card wasn't there in the morning, as I make go through all the junk mail I have acquired each Thursday morning and put it out for recycling.
b. This means the card came through the letter box three days after the delivery had been made.
c. A logical conclusion is that someone had the card, with the intention of picking the parcel up pretending to be me.