Seller Sent Extra Items

[deathpixie]

The seller I purchased from sent me the items I purchased as well as additional items. The seller tells me the other items were sent to me by mistake and is DEMANDING that I forward the items on to the correct buyer. I see no reason why I should take time out of my day to go to the post office and ship things to someone else just because the buyer I purchased from screwed up. I made what I thought was a reasonable offer (I keep one of the additional 13 items I was sent and forward the rest on), the seller said this was "completely unacceptable" and made no counter offer, and has told me to forward the items on as well as threatening "ebay has been advised of this". If the seller were being nice it would be one thing but the way they're talking to me makes me not want to go out of my way at all to do them any favors. I don't believe I am under any obligation to send anyone anything. Am I? What should I do?