You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I serve you?

USER: Owing to an emergency, my business conference got postponed. So I want you to change my existing reservation.

ASSISTANT: Sure, may I know your name please?

USER: Sure, I have a recent reservation with name Donna Thomas.

ASSISTANT: Please stay online.

USER: Sure.

ASSISTANT: Thank you for your time. Sorry, there is no reservation matching with your name in our portal to make changes further.

USER: Ok, no worries at all. Thank you for your information.

ASSISTANT: Thank you for reaching us.