Customer: You don't seem very comfortable with this; maybe you could pass it on to another engineer..?

Situation:
I'm a System Management team engineer. Customer is asking about licensing (which is a different team) and has that very rude habit of asking a question, doing a small pause in which I start answering, and then speaking again and cutting me off; thus causing me to seem very splutter-y. Since I couldn't give a definitive answer to his licensing question he doubts everything and thinks I can't do crap. And he's the one who wants me to sit on an upgrade with him because he's too afraid to follow documentation.

His words to me: "Have you ever done this upgrade before; I mean are you familiar with it?"

Me: "Nope since it's not policy to sit on upgrades as we are a break-fix center but I've directed other customers to do it through the documentation I've given you and they got on fine."

Seriously doubt the capacity of some of these guys to do an upgrade where there's step-by-step videos and very legit documentation (never mind this upgrade uses the tool which has the best record for not breaking)