You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I'm Helen Walker.

ASSISTANT: Yes, Helen.

USER: My business meeting has been postponed. So, I would like to change my reservation.

ASSISTANT: Fine, please be on hold.

USER: Sure, take your time.

ASSISTANT: There is no reservation found under your name to do changes in that.

USER: Ok, no issues. Thank you for checking.

ASSISTANT: Thank you for choosing us.