So, say you buy a $59 shoe and a $25 shoe, thus you can then use the $30 off coupon. Once you receive everything, you then send back the $25 shoe since its free shipping. Thus, you have already used the $30 credit, and since it was not deducted off both shoe prices, but just as a coupon code overall, you will get the full credit for the pair you send back, thus leaving you to get the $59 pair for $29. Pretty easy. I have done this with similar promotions in the past, and it has worked like a charm.