Man that really sucks JJ, personally I would contact him because he made a "promise". For all we know he probably never sent you the item but let's not go that far since only you two would know.
But its really petty of him to have blocked you, and based on that its obvious he had no problems cheating you or lack of compensation for the error.
I'm an honest guy when it comes to such issues and have no problems adjusting things to make another person happy. But that's me being someone with integrity. All you can do is leave a negative feedback and not deal with him. If you feel its worth fighting, do so if not leave it be and never deal with him again.