Thanks for the reply Taltop. Just for the record I am still waiting for the money, and it is now four months since my trip.
I was told (by the chief pilot 737 fleet HNA,) that they only have 10 expat pilots on the 737 out of a total complement of over 800 pilots. Maybe if they reimbursed people for their trips, then they would be a bit more proactive in their prescreening selection and not waste so many peoples time. As things stand at the moment pretty much every agency with a website and a phoneline is recruiting for the Chinese market, as there is no cost involved to the airlines. (Shenzen notwithstanding, they are quick with reimbursement.