You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I want to change my existing reservation because my IIT Conference Meeting got postponed. Can you help me?

ASSISTANT: Sure, I can search your previous ticket.

USER: Thank you.

ASSISTANT: Can you please tell me your name?

USER: Sure, I am Dorothy Anderson.

ASSISTANT: Sorry Anderson, there is no reservation found with your name in our system data.

USER: Ok, not a problem. Thank you for your valuable time.

ASSISTANT: You are welcome. Thank you for choosing us.