You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I give assistance to you?

USER: Can you please help me to change my existing reservation as I am sick and cannot go on the trip?

ASSISTANT: Sure, we are glad to help you to change it.

USER: Thank you.

ASSISTANT: On whose name, your reservation has been done earlier?

USER: On my name, Melissa Smith.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Thanks for your time, there was no reservation found on your name to change your reservation.

USER: No problem, my mother may have done it already. Thank you anyway.

ASSISTANT: Thank you for availing our service.