Does anyone know how I can book a return flight from Nashville to Manchester via ORD in C class. Specifically I want to take advantage of the JAP50BMI fare which weighs in at £1800 ish.

ITA shows the fare including the coach UA sectors but are there any other websites other than Orbitz that can be used to book. I am UK based and travelling to the US via 'other means'!

Also on a fare of construction of multiple fare types which takes priority? It is highly likely that I will have to change the dates of the tickets prior to the first sector - is that possible when ITA is showing S class and J class combined?

Cheers
Alex