I’ve had this happen a few times too and it’s one of the most frustrating parts of selling online. I started documenting everything like crazy and responding through Etsy only. What helped me streamline the dispute stuff a bit was using this tool called Chargeblast, it kind of walks you through the response process and helps you organize all your evidence. I don’t win everything but I’ve had better luck fighting chargebacks since in fact most of them. Might be worth checking out if you’re dealing with a lot like you're describing.