You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, what can I do for you today?

USER: Can you please help me in changing my reservation?

ASSISTANT: Sure, we are glad to help you.

USER: Thank you.

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

USER: I am Sandra Martin.

ASSISTANT: Ok, wait for a while.

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 our services.