You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: Myself David Walker.

ASSISTANT: Nice to meet you David.

USER: Can you please help me to change my existing reservation, due to some abnormal weather conditions?

ASSISTANT: Sure, I will help you with the change of flight reservation. Please wait for a moment.

USER: Thank you. Sure.

ASSISTANT: Thanks for waiting. But I am sorry to say that there is no flight reservation on your name to change it.

USER: Ok, that's fine.

ASSISTANT: Thank you.

USER: Thanks for the help.