You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any assistance from us?

USER: As my meeting with my clients has been postponed, can you please do me favour by changing the existing reservation?

ASSISTANT: Sure, I will help you. Could I know your name please?

USER: My previous booking has done with my name Donald Harris.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Donald, I haven't found your previous reservation in our portal to change further.

USER: Ok, not an issue. May be something went wrong while booking the ticket. Thank you for providing information.

ASSISTANT: Thank you for opting us, have a great day.