In a global view, yes we do in some cases. However, in the real sense, each vendor on our platform is in charge of defining his/her returns, refund, and guarantee policies either for their shops or for some particular product. Reasons why we encourage all customers to read all shop/product policies before issuing payment.
Muyang ONLY ensures that vendors respect the policies which they publish on our platform.
More details about this are on the Guarantee and Refund Policy