You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

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

ASSISTANT: Sure, we are here to help you. Can I have your name to check the details in our reservation list?

USER: Cynthia Thompson here.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Unfortunately, there is no reservation exist on your name to proceed further.

USER: That's ok, no problem. Thank you for helping me.

ASSISTANT: Thank you for contacting us.