Assuming that your buyer has a storage space at the Kennards outlet (and isn't an employee there):
I'd be contacting the Kennards outlet directly, explaining the situation, and asking them to check if the item was sitting there on the shelves.
If they answer "yes", ask them to contact the buyer and tell him / her that their item is awaiting collection - and contact the buyer yourself, and tell them the same thing. If the buyer rents storage space there, they'll have the contact info.
If they answer "no", ask them to confirm that the item was delivered there (quote them the name of the person there who signed for it), and ask when it was picked up, and by who. Whoever picked it up will have had to have provided ID. Then contact the buyer, and politely explain that the item was picked up by someone who provided the relevant ID, and diplomatically ask them W T F they're playing at.
Of course, if your buyer works at that Kennards and has their mail delivered there during the day, you'll get to talk directly to them. Joy!
