United States Postal Service

Shipped a $150 product returning it to a warehouse seller, tracking confirmed it arrived on the 17th and was sent out, yet it has been four days and no one has been available to help me. The seller claims they never received it and can not process my refund until they do. No one there has been available to assist me whenever I call. How can a federally run office be this incompetent?! It should be shut down!