You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Nancy Hernandez here.

ASSISTANT: How can I assist you today?

USER: Due to some health issues, I want to postpone my trip to some other dates. Can you please change my trip dates?

ASSISTANT: Sure, please give me a moment.

USER: Sure.

ASSISTANT: There is no reservation found under your name.

USER: That's ok, thank you for your information.

ASSISTANT: Welcome, have a great day.