You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I want to change my existing reservation due to sudden postpone of my trip dates. Can you help me with that?

ASSISTANT: Sure, will you please mention your name?

USER: I am Ronald Anderson.

ASSISTANT: Please give me a moment.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no reservation found under your name.

USER: Ok, no problem. Thank you for your response.

ASSISTANT: Welcome, have a great day.