You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I would like to change my existing reservation, can you help me in that?

ASSISTANT: Sure, can I know your name?

USER: Sure, myself Mark Jones.

ASSISTANT: Wait a minute.

USER: Sure, I will wait for your response.

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

USER: That's ok, no problem. Thank you for the information.

ASSISTANT: Thank you for opting our agency.