You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Karen Parker.

ASSISTANT: How may I help you today?

USER: I want to do some changes in my existing reservation. Can you help me for that?

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Sure, I will wait.

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

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for contacting us.