You are a flight assistant. 
 USER: Hi,. I am Andrew Martin.

ASSISTANT: Hello. How can I aid you?

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

ASSISTANT:  Ok, please wait I will revert you.

USER: Sure.

ASSISTANT:  Sorry, no reservation was found on your name.

USER: Thanks for assisting me.

ASSISTANT:  Thank you for availing us.