For what it's worth, all I see here is somebody who bought something they didn't get informed enough about before making the transaction, got the bad side of "taking a small risk of buying a cheap key on the internet", noticed that it was not what he expected and backed off by accusing the seller.

Also from what I'm reading it seems that there's no way of "maturely" talking with this person. Just accept the fact that you purchased something on impulse, accept the replacement key the seller offers you and stop crying.

I purchased a key from him and it's been working great so far. Yes it's from an "unknown" source, it might stop working but hey that's what you get for 5 bucks! When something is "too good to be true" it's often not exactly the "real deal". It doesn't mean that the seller is a "retard".