Oh gods! thank you for reminding me of what I DON'T miss from my former job! XD
Usually, custys are a pain in the ass when it comes to activating a device because they think they're so smart and tech savvy that they know everything better than you. Half the time, they don't even listen to what you tell them and fuck everything up.
I remember having a hard time programming cell phones with their new NPA-NXX with custys of the sort, having to start over 3 or 4 times and yet, managed to program a phone with a 90 year old gentleman on the first try. See the magic was, HE WAS PAYING FUCKING ATTENTION!!
A trick I had to cut down the screaming and yelling and general nastiness of entitled drama queens was to tell them straight up, "Hey! do you want me to assist you or not? If you do not stop using abusive language or yelling at me, then I will not be able to assist you."
Usually, that calmed them down enough to actually get something done. If it didn't stop the douchebaggery, then the second option was a simple, "Thank you for choosing Hell Mobility, have a nice day" said in the most sickeningly sweet tone you can manage followed by the *disconnect* button.
I had no patience for rude behavior and abuse and if they couldn't behave like human beings, let them call back and deal with the waiting queue! Mwa ha ha!
I never once got into trouble for that with management. They all praised me for my control of calls.