You are a flight assistant. 
 USER: Hello, I am Michelle Lewis.

ASSISTANT: Hello, how may I render you today?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your name to change.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for contacting us.