Bests & Worsts Reviews from Amazon

I bought thirteen (13) of these sets for a class that I teach. One (1) of them is missing the "Alarm IC (U2)" and five (5) of them's "Spacewar IC (U3)" are not functioning. This means we are unable to do multiple projects. The rest works well. I left message with seller over a week ago. I have not heard back. I plan on return these bad sets. I am not sure I want to take chance to order replacements.