As [MENTION=572319]Chukiechz[/MENTION] mentioned, the only way to select seats with CA is to call them. Unless it's booked on their site directly, seat selection (and anything other than validating your ticket.... and not in English) is not allowed for booking made through UA revenue, UA awards, Expedia, BudgetAir, Kayak, etc. - anyone other than making a direct AirChina.<whatever> booking.