You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I ant to change my existing reservation due to some personal problems. Can you help me?

ASSISTANT: Sure, I will help you for this. Let me check your reservation status in our records.

USER: Thank you.

ASSISTANT: For changing your reservation. May I know your name please?

USER: Yes, I am Timothy Walker.

ASSISTANT: Please wait for moment.

USER: Sure.

ASSISTANT: Walker sorry for inconvenience, no reservation is available with your criteria.

USER: Ok, not an problem. Thank you for your information.

ASSISTANT: Thank you Walker for reaching our agency.