Amazon FBA partial refunds can be configured by return reason
According to an official Amazon Canada announcement, FBA sellers in the United States, the United Kingdom, Germany, France, Italy, Spain, and Canada can now choose which customer return reasons qualify for partial refunds. There are two ways to configure this: set different refund rates by return reason for all ASINs, with up to three configurations; or upload an Excel file specifying the products and return reasons eligible for partial refunds. Products or reasons not included will continue through the standard returns process. For sellers already enrolled in the program, eligible return reasons will continue to offer customers partial refunds. Partial refunds are available only to customers who meet the eligibility requirements.
FBA sellers in the United States and several European countries can set partial refund rates by return reason, with configuration options for all ASINs or specified ASINs.
Source:Amazon Canada Official Announcements · sellercentral.amazon.ca