I have bought a class E ticket from Boston to Shanghai, via Hong Kong. I originally planned to fly on Dec 20, but now I found that I can leave earlier and want to depart on Dec 15. As there is no more class E available, the customer service representative put me on standby list. Does anyone know the likelihood to get on that flight CX811(Dec 15)? They also tell me I need to pay money if I want to downgrade to economy class. Anyone can help? My sincere thanks.