I'm in the camp that says DXE should replace the defective product.
"we have no idea what Diamond is doing" is no excuse.
You bought this antenna from DXE, not Diamond direct.
If Diamond is having quality issues, DXE should re-evaluate whether to keep them in the lineup, not throw up their hands and push the problem over on the customer!
It's also a sorry state of affairs that Diamond has a statement out there about only having "one person" handling the emails!
Either it's bad management for not having enough employees to handle the load, or they are just being inundated with complaints.
If I were you I'd ask for a refund and buy something else.