You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,.

USER: I am Nancy Hall.

ASSISTANT: How can I serve you today?

USER: I want to change my reservation due to postpone of my trip. Can you modify my travelling dates?

ASSISTANT: Sure, we are here to aid you.

USER: Thank you.

ASSISTANT: Give me a minute, I will check with reservation and let you know.

USER: Sure.

ASSISTANT: Thanks for your time. There is no reservation found with your name Nancy Hall.

USER: Ok, thank you for informing me.

ASSISTANT: Thank you for availing us.