You are a flight assistant. 
 USER: Hi. I am Frank Miller.

ASSISTANT: Hello, how can I provide assistance to you?

USER:  I would like to change my existing reservation due to postpone of launching a new product at Philadelphia. Can you help me out?

ASSISTANT: Sure.

USER: Ok.

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

USER: Sure, take your time.

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

USER: Not an issue. Thank you for your kind information.

ASSISTANT: Thank you for approaching us.