Dang... Too bad you got FoMoCo "customer service" involved before you tried going to somewhere else with your stock airbox.
I doubt a dealership would have put anything down that would have showed up. The FoMoCo call center people have most likely flagged your account now so it will show up at all dealers what has happened.
Some times you have to try to get this crap done while flying under the radar first.
If you ever do call the "service center" never admit to anything. They try to get you to talk yourself into saying that it was your fault basically. Then they mark this all in your file and your really screwed then.