I once bought a front load washer from Sears with my Mastercard. I then had them correct it and put it on my Sears card instead to get a discount off of it. They credited my Mastercard twice, and then charged the discounted price to my Sears card.
I left the amount I owed to Sears in the bank thinking eventually they'll correct this mistake and re-charge my Mastercard. Well, it's been about 4 or 5 years now, and I haven't seen it yet, so I'm thinking they won't ever charge me back.
So I scored myself a free washer plus they paid me the difference between the discount and the full price to take it off their hands.
Guess which one I voted for up above?