You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I address you?

USER: I want to change my existing reservation due to prepone of my meeting dates. Can you please help me in that?

ASSISTANT: Sure, please let me know your name to check the reservation list and revert to you.

USER: Myself William Parker.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting William Parker, I have gone through the reservation list but could not find any active reservation by your name.

USER: Ok, no problem. Thank you for checking.

ASSISTANT: Thank you for approaching us.