You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello. how may I address you?

USER:  I want to change my existing reservation. will you help me?

ASSISTANT: Sure, I am here to help you. Can you please help me out with your name?

USER:  Sure, My name is Jonathan Green.

ASSISTANT: OK, Please stand by I will check and get back to you. Thanks for being patient. Unfortunately there is no reservation found against your name.

USER: OK, Thank you for your information.

ASSISTANT: Thanks for reaching us, have a nice day.