You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I serve you at this moment?

USER: I am Christopher Lewis. Please can you help me to change my reservation?

ASSISTANT: Sure, please wait for few minutes.

USER: Sure.

ASSISTANT: There is no existing reservation found on your name in our data base.

USER: Ok, thank you for informing me.

ASSISTANT: Thank you for reaching us.