If you are seeking to protect others, I recommend you follow up on Greg's offer before taking the next step. Two problems from the same seller can be suspicious.

If you are wondering whether you have an ethical obligation to report troublemakers, I would be hard-pressed to think of such a rule. Many people have deals that go sour, and they do not report it to everyone. Also keep in mind that this is a public board - not a CC>CC board - so your post would go beyond club members.

If you are asking whether it is ethical to make your dispute public, I see nothing wrong with it. Just be aware that some people have used The Chip Board for that purpose and had it backfire when others told them the seller had an excellent reputation or they disagreed with the posted commentary. Two problems from the same customer can be suspicious.