Not cool. You cannot just threaten not to give the person the money back because of how this person publicly reminds you of that. I'm pretty sure it wasn't a part of the initial deal, so you cannot invent the rule now.
And not reacting to what Pmalek said about you closing the thread and deleting blog history when it wasn't a successful one also doesn't make you trustworthy. Trust is an important thing on this forum, and the way you're behaving clearly doesn't help you to establish a good reputation here.