This is why it's a good idea to state your terms clearly up front. You should make it right because mistakes do happen, but how far should we be expected to bend over backwards. Having a time limit prevents customers from scamming you, too. How do you know 2-3 years later that it's even the same snake? And it prevents the unreasonable requests like refund plus lost revenue that I've seen people come back with. Customer service is all important but customers have to act reasonably too.