I would not buy from a seller publishing this policy. And I won't knowingly buy from any seller whose unpublished policy it to post retaliatory feedback when a customer posts a negative experience. If I buy from a seller and get bad service such as the part was not really in stock when auctioned (and not noted as such) or arrived a month late, I should be able to post a negative stating the facts and no negative is appropriate in retaliatory response.