バンコクエアウェイズの予約変更できますか？

Re: バンコクエアウェイズの予約変更できますか？

下記サイトからの情報通りにしてみてください。
http://www.bangkokair.com/en/passenger-services/reservation-assistance.php

Re: バンコクエアウェイズの予約変更できますか？

８００バーツの手数料で変更できる様ですね。MY　BOOKINGから
変更できるみたいです。



ANY TIME
PER COUPON CHARGE THB 800 FOR REISSUE/
REVALIDATION.
WAIVED FOR ILLNESS OR DEATH OF PASSENGER.
NOTE - TEXT BELOW NOT VALIDATED FOR AUTOPRICING.
1.DATE/FLIGHT/CLASS - PERMITTED WITHIN TRAVEL REST
RICTION WITH A CHANGE FEE THB800 PER CHANGED SECTO
R OR PER CHANGED FARE COMPONENT. THE NEW ITINERARY
FARE MUST BE EQUAL OR HIGHER. IN CASE THE NEW FAR
E IS HIGHER COLLECT THE DIFFERENTIAL FARE. THE ORI
GINAL NON REFUNDABLE AMOUNT REMAINS NON REFUNDABLE


　If your original booking has been made directly through the Bangkok Airways website, you can view your itinerary and/or make any necessary changes at the click of a button. Simply go to the ‘My Booking’ tab on the right-hand side of our website, fill in your booking reference, first name, and last name and then click ‘SEARCH’. Select the ‘Exchange Flight’ menu on your right-hand side to change your flight.

FAQを読んでませんでした

他の方の回答にあるように、チケットコンディションによって変更できる場合と出来ない場合があるようです。訂正させていただきます。

Bangkok Airwaysのサイト

HPとは、すなわちBangkok Airwaysの
WEBサイトのことなのでしょうか。
ならば、

Manage Your Booking

Original bookings made through www.bangkokair.com

If your original booking has been made directly through the Bangkok Airways website, you can view your itinerary and/or make any necessary changes at the click of a button. Simply go to the ‘My Booking’ tab on the right-hand side of our website, fill in your booking reference, first name, and last name and then click ‘SEARCH’. Select the ‘Exchange Flight’ menu on your right-hand side to change your flight.

Where more than one change has already been made to an existing booking, customers will not be able to utilize the ‘My Booking’ function and will need to contact the Bangkok Airways Call Centre directly.

FAQs
Q:How do I change my flights ?
A:You can change flight by using our online e-services or contact us(link) directly. All flight change are base on ticket conditions, Fees may apply.

要するに変更可能な料金（サブクラス）なら可能だと言うことです。