I commented above that the initial questioning was fine.
> "or you don't know what your doing,"
That though was unprofessional, and should be addressed as such.
What would you reply today?
"Yeah, well I had sex with your wife!"
Or just offer over-inflated estimates since they won't accept something realistic anyway.
"We don't know because we've never done this before, and we can only compare to the most similar work we've done, and any existing data."
Before I could say more, they I interrupted: "You have to know, it's your job, or you don't know what your doing," or something along those lines. It was the most heated I've felt. I know what I'd reply with today, but I was younger and more naive then.