Opened computer games are explicitly prohibited from return and you are not obliged to provide ANY refund at all. They are specifically stated as excluded in Amazon's Returns Policy as well as (if you really want to know) The Consumer Contracts (Information, Cancellation and Additional Charges) Regulations 2013 (Section 28 (3)(b).

HOWEVER - and it's a big however - if such an item is returned, there is no real way to "deny" the return on the Amazon system and any customer putting an A-Z Claim in will instantly be refunded in full if the tracking shows it came back 72+hours ago. And they will deny any appeal, because you haven't refunded within 72 hours, end of.

My advice is always to partially refund. That way an A-Z Claim will not get processed automatically, they will write to you and you can advise that it was returned opened in contravention of policy, there is no entitlement to a refund but you have provided a partial refund anyway. Oh - and report the customer for violating returns policy, please, not enough people do this (report a violation, top of Account Health page)! It won't help stop an A-Z Claim, they dont' check for violations, but if enough people did it Amazon would appreciate it's a problem.

The portion you refund is very much up to you, in our experience anything less than 50% stands a chance of still being refunded in full from your funds by A-Z, 50% or more they will sometimes close, sometimes refund the customer from their own funds but generally you're left alone - either way they shouldn't impact your metrics,. The problem with Code in Box games is you can't tell if the code has been used or not, so they are basically worthless when they come back.

Hope this helps some :) Wish there was a way to "Deny" a return, if there is and I've missed it all this time please let me know!