I work at home Depot and I sometimes have to take a call. If someone tries yelling at me over the phone, I hang up on them wait about 30 seconds and call back and say "sorry about that but I think the call got disconnected, what were you saying?" Most of the time they realize if the wanna be a dick head then they aren't gonna be helped so they change the attitude. The ones who continue to yell, I'll make something up and basically say there's nothing we can do to help them (even if there is something I can do for them) and end the call.