Without seeing the advertisement itself it is difficult to understand where the confusion stemmed from. "It was digital but it wasn't" is difficult to decipher. The technology can be confusing. If the advertisement was actually factually incorrect, the seller should pay shipping both ways. If the advertisement referred to a product and was accurate (but perhaps didn't describe it completely), then the seller could reasonably expect the buyer to have researched or asked about the details of the product before bidding, and so is not only not obligated to pay for the return shipping, but could make a strong argument for declining the return completely. If that was the case, then the seller's willingness to take the return is rather generous, to start with, and it wouldn't be necessary for the seller to offer more consideration.