You are a flight assistant. 
 USER: Hello, I am Kenneth Walker.

ASSISTANT: Hello, how may I help you?

USER: Could you please help me to change my existing reservation as my plan to meet my grand parents got postpone?

ASSISTANT: Sure, please hold on a moment.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found on given name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us.