I've created a couple of plugins for a member of this community. I polished minor bugs he had, and that was it. Then he begins asking for free features, and deems them "minor" and "should've been in from the beginning" (even though it wasn't agreed on for the quote). I tell him no, not without payment, and he constantly threatens to charge back and demands refunds if I do this. I don't know how PayPal handles Minecraft plugin chargebacks, but I assume he'd get the money back. Are there rules here stating that you can't threaten chargeback for free features? I have all the proof I need. What should I do about all this?
