You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. What can I do for you?

USER: My name is Melissa Miller. My plan to visit a function is postponed as of now, I want to change an existing reservation.

ASSISTANT: Sure, I will help you.

USER: Ok.

ASSISTANT: Please give me a moment to check. Thank you for waiting. Sorry, there is no reservation found on your name.

USER: That's fine, thank you for your help.

ASSISTANT: Thank you for reaching us, have a nice day.