不好意思，我记得之前爬到这篇版友的官方回信，好像已经有官方答案了？
这封美国官方回复文件，就有提到，退货要带商品回任何一家Costco退货
原PO似乎有点误解官方回函的意思。
(以下翻译）
若您对商品不满意，就请您退回商品(return the product)到任何一家Costco。
尽管我们没有强制规定退货必须包含产品包装(product packaging)，
但若您仍保有(产品包装)的话，请连同产品包装一起退回给我们。
※ 引述《onom (通车)》之铭言：
: 应该可以没单没东西退钱
: 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
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
: 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)
: