Recently, I noticed I have lost a user from my buyers list. Upon referencing my PayPal account, it seems the user claimed they payed but did not recieve the software. This was the first person to buy the plugin, as detailed by my books and the total downloads number exceeds the buyer list size. I probably would've given a refund if asked but instead, I have a blemish on my PayPal account, in a fraudulent light. Should I fight it? Is there any way to prove the receipt of software?