You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Can you please help me to change my existing reservation?

ASSISTANT: Sure, I am here to help you.

USER: Sure, I am Carol Thomas.

ASSISTANT: May I know your name please?

USER: Carol Thomas.

ASSISTANT: Sorry to inform you that there is no active reservation on your given name.

USER: Ok, no problem. Thank you for checking.

ASSISTANT: Thanks for contacting us.