You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I am Sandra Hernandez. Owing to an emergency, I want to change an existing reservation.

ASSISTANT: Ok.

USER: So please help me in changing the reservation.'.

ASSISTANT: Sure. Please wait for a while, I will check your reservation.

USER: Sure.

ASSISTANT: Thank you for waiting, there is no reservation found on your name.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for approaching us.