You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I support you today?

USER: I just want to change an existing reservation as my plan to meet my grand parents got postpone. Can you help me?

ASSISTANT: Sure, could you please let me know your name to check the reservation?

USER: I am Daniel Taylor.

ASSISTANT: Sorry, there is no reservation found on your name to change.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for contacting us.