You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I support you?

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

ASSISTANT: Sure, we are here to help you. May I know your name please?

USER: Sure, myself Jerry Williams.

ASSISTANT: Please wait for a while.

USER: Sure, I will wait for your response.

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

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

ASSISTANT: Thank you for choosing us.