I have an upcoming trip where I'm ticketed with a Z fare SFO-IAD-FCO. I wanted to change the domestic leg to LAX-IAD ... the 1k desk (twice) told me that they have to reticket the whole trip, and since Z isn't available IAD-FCO, I'm out of luck. Of course I've already got a Z seat on that leg ... even if I cancelled the whole thing, it's unlikely that my Z seat would go back into inventory. But, still.

I've encountered something similar on other airlines before; the inventory folks can see the silliness of the catch-22 and can hold it to make the cancel-rebook an "atomic" transaction. I can't seem to get UA to do this ... anyone have a different experience or any advice? Thanks.