You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Emily Robinson.

ASSISTANT: How can I assist you?

USER: I want to change an existing reservation, so please help me in changing the reservation.

ASSISTANT: Sure, let me check your details in our database.

USER: Ok.

ASSISTANT: Sorry, we couldn't found any reservation in our database.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for reaching us.