You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I guide you today?

USER: Can you assist me to change my active reservation?

ASSISTANT: Sure, I am gleeful to help you.

USER: Thank you.

ASSISTANT: On whose name, you want to change the reservation?

USER: Donald Clark.

ASSISTANT: Ok, please standby.

USER: OK.

ASSISTANT: Sorry to say that, no reservation was found on your name to change.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for availing us.