Sorry but you just learned the hard way to secure your very expensive electronic products. Plus why should China Air help you? You're the one that was irresponsible with your phone. Would you have stuffed $600 in the seat pocket and gone to sleep? Most likely not so why would you do it with your phone?
I didn't think they should help me, but they were totally not being helpful by asking me to "remember" where I put it. They insisted that I lost the phone, which is clearly not what happened here. One attendant even denied that something like this has never happened before, while another attendant openly said it happens very often.
Thanks for all the tips. Yes indeed, lesson learned.