I'm 99% sure that is the problem. Though being that he was driving on them assembled wrong, he may have damaged them.From what I could gather, you installed them very wrong. If my assumption is correct, you're risking the lifespan of your suspension parts by having them installed so improperly. I would find someone that will help you; that's what I did. It's like $200 for installation from a shop or $500+ for new suspension.
Hopefully I helped you a bit