Bad Customer Service is Bad Customer Service! (I'm going thru this right now with PerformaceBike) I don't think you are bieng unreasonable, out-of-line, or imagining things. And I gotta go with everyone else: you're paying a chunk of change for a custom bike and he's guesstimating the size??....treating you in a dismissive and condescending manner??
I'd agree on either calling IF and seeing if there is anyone else in your area that will do custom fitting or - I know how much you love it - but maybe look at another custom builder?? Luna Cycles are highly recommended, as is Seven, someone here sang the praises of Rodriquez, and of course Rivendell. Let us know how it turns out hun - keeping you in my thoughts!
Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body, but rather to skid in sideways, champagne in one hand, strawberries in the other, body thoroughly used up, totally worn out and screaming: "Yeah Baby! What a Ride!"