You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: I am very busy with my meetings, so I am not able to complete my trip. Can you please help me in changing my existing reservation?

ASSISTANT: Sure, may I know your name to check the reservation?

USER: My name is Barbara Thompson.

ASSISTANT: Sorry, there is no reservation with your given name.

USER: That's ok. Thank you.

ASSISTANT: Thank you for the information.