You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Jerry Clark.

ASSISTANT: How may I guide you today?

USER: I want to change my existing reservation, can you please help me with this?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Please wait for a minute.

USER: Sure, take your time.

ASSISTANT: I am sorry to say that there is no reservation found.

USER: Ok, no problem.

ASSISTANT: Thank you for reaching us.

USER: You are welcome.