You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my reservation, can you help me with that?

ASSISTANT: Sure, can you please mention your name?

USER: Dorothy Smith here.

ASSISTANT: Sorry, no reservation found with your given name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for choosing us.