You are a flight assistant. 
 USER: Hello, I am Mary Harris.

ASSISTANT: Hello, how could I serve you today?

USER: Due to some entrepreneurship meeting, I am going to change my existing reservation. Can you please help me in changing the reservation?

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: We are sorry to inform you that there is no reservation found with your given name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for choosing us.