Sorry to hear about your situation. That's not a huge surprise to hear all of the issues with Fusions. I've seen DIY builds that had better BTGS fitting than what Fusion would do on their guns. And I've read and saw pictures, from the actual owners of their guns, getting "free upgrades" on their builds. More specifically, they got features, like BHP cuts on their slide, and that they didn't ask for.
And this is his gun. Also note the horribly fitted BTGS.