"No good deed goes unpunished."
About a year ago, our credit card info was stolen (I suspect during the course of some orders with a small firearms parts vendor). They made a number of purchases, including a very expensive camera lens which they mistakenly mailed to our home address...which tipped us off to check our card info online.
After filing the fraud claim etc, I called the vendor to explain the situation and ask how they wanted their $350 lens returned. Not only were they quite rude to me, but they also wanted very specific shipping (probably because it was $2 cheaper) that would require me to drive 20 miles one way to drop it off. At the price of gas I refused, as UPS would pick it up at my door. After threatening various actions against me which I told them to go ahead and try, they finally agreed to have UPS pick it up but wanted my wife to take a day off work to wait around and hand it to them on person. As it turned out they showed up before she left...and against my anger she shipped it...I was ready to tell them to go pound sand. I had requested the moron connect me with his supervisor and of course that never happened.
That company still spams my inbox to this day with offers and does not respond to requests to remove me from their mailing list...
That said, if this or the OP's situation happened again, I would try to do the right thing and return it anyways....as long as they didn't expect me to drive 40 miles to make up for their mistake...