As a buyer you cannot cancel a transaction even if you have a legitimate reason to do so. You might have lost the item, it could be damaged ... or you might have sold it on another website the same day for example. Well that's the thing, their terms and conditions reveal that you are NOT allowed to sell your item on any other platform (don't think that's even legal). So they use this paragraph to tell you that they will not refund you the sale fees you owe them even though the sale was cancelled and you have not sold anything. Be careful sellers, make sure you WILL sell 100% the item you put there.