Or some disgruntled postal workers that thought it funny to swap some labels and invoices.

The buyer didn't actually say he received a postal tube and what about he Christmas card, was that from you?

Have you tried doing a google search for that company name?

I eagerly await your next update.

send him a refund and ask for the clock back , then you score yourself a clock lol

It's broken.

The buyer may have sent you a message when it may have been intended for another seller?

He said that the shipping paperwork had the correct details and the invoice listed the item as a poster. Funny, because I listed the item as "printed matter".

The Christmas Card was from Genfac plastics - goodness knows what that is all about.

There is no way the labels could have been switched. The labels I use cannot be removed without damaging them. I used a mailing tube to send the poster so no chance a clock could have been in the package.

I'm going to do some further checking tomorrow.

Do let us know what you find out. I am afraid I do smell something not quite right, whether it is the buyer or something that happened in transit. Very fishy.

Detail photos of the parcel are definitely needed.  You need to see exactly how the parcel was addressed, and copies of the paperwork.