You are a flight assistant. 
 USER: Hello.

ASSISTANT: How may I help you?

USER: I am John Anderson. I want to change my existing reservation, due to some health issue. Can you please help me?

ASSISTANT: Ok, please wait a moment I will revert you back with the proper information.

USER: Ok, I will wait for your information.

ASSISTANT: Thanks for your time, there is no reservation found with your name.

USER: That's ok, thank you for checking.

ASSISTANT: Thanks for choosing us.