If you ring the eService Centre, can they help you get a Gold/Diamond seat guarantee or can only the reservations department do that? Yes they can but they will only do it for fares that are sold online
And can they help you get the seat guarantee 24/7, or only during normal HK working hours? Yes 24hrs a day 365 a year.
And if you ring the eService Centre to complete a booking, and you pay via Citibank CX credit card, will you get the bonus miles that you would get if you did an online booking? Yes because the whole process is treated as an online transaction even though you did it by telephone
Thanks!