不好意思，我記得之前爬到這篇版友的官方回信，好像已經有官方答案了？
這封美國官方回覆文件，就有提到，退貨要帶商品回任何一家Costco退貨
原PO似乎有點誤解官方回函的意思。
(以下翻譯）
若您對商品不滿意，就請您退回商品(return the product)到任何一家Costco。
儘管我們沒有強制規定退貨必須包含產品包裝(product packaging)，
但若您仍保有(產品包裝)的話，請連同產品包裝一起退回給我們。
※ 引述《onom (通車)》之銘言：
: 應該可以沒單沒東西退錢
: Subject
: Other - The issue of glyphosate of American Quaker OAts
: Response By Email (Sue G.) (05/27/2016 10:27 AM)
: Dear Hxxxx
: Thank you for contacting Costco.
: Our goal is to exceed your expectations on every product you purchase at Costc
: o. But we also recognize that sometimes we fall short. That’s why we offer wh
: at we believe is one of the best satisfaction guarantees in the industry.
: If you are not completely satisfied with your Costco purchase, simply return t
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
: he product to any Costco warehouse. Please include the product packaging if yo
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
: u have it, although we do not require it for a return to be processed. We also
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: prefer that you provide your original receipt, but if it is not available, we
: will do our best to process your return without it.
: Thank you,
: Sue G
: Member Service Center
: Costco Wholesale Corporation
: Customer By Service Web (Hxxx) (05/27/2016 07:02 AM)
: