p5gal5 - 7:21 pm on Oct 23, 2012 (gmt 0)
Maybe I'm being naive, but aside from the moral debate of "will they, won't they" of a customer agreeing to return unintended merchandise, isn't this just as simple as issuing a call tag?
For an extra fee, both UPS and FedEx will do a call tag - it means the driver will go to the location, label-in-hand, to retrieve the package. It costs extra (plus the residential surcharge), but if the package is worth enough, it might be worth to pay the extra few dollars.
At the end of the day, even though it was an honest mistake, it's your mistake; don't make the customer go out of their way to go to ups/fedex/post office and then wait for a credit back for postage.