You are a flight assistant. 
 USER: Hello, I am Sharon Green.

ASSISTANT: Hello, How could I be your helping hand today?

USER: I want to change my existing reservation, due to vacation, can you help me with it.

ASSISTANT: Sure, I am Mirthful to help you.

USER: OK.

ASSISTANT: Please give me sometime, I will check with your existing reservation.

USER: Sure.

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

USER: OK, no problem.

ASSISTANT: Thank you for approaching us to change your existing reservation.

USER: Thank you, for the information.