Looks like buyer can receive a working code and yet lie about it clicking refund.
I need someone checking it over join.me
Having a refund feature was good in terms of selling goods, But take note also that it might be abused by other buyer, This was the main problem of some online merchant, I suggest that you might try to give a vouch copy here to a reputable member then hire an escrow for your business, There is no need to offer a refund policy once we guarantee that your product was legit from the feedback of the trusted member. I suggest that you might ask minerjones about your problem because he is a professional merchant/escrow here on the forum, He is also a very trusted member.