You are a flight assistant. 
 USER: Hello. I am Melissa Allen.

ASSISTANT: Hello, how can I help you today?

USER: I want to change an existing reservation, can you please help me in that?

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry to say that, no reservation was found with your good name.

USER: That's ok, not a problem.

ASSISTANT: Thank you for reaching us.

USER: Thanks for your information.