You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

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

ASSISTANT: Sure, can I have your name please?

USER: I am Carol Mitchell.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting ,there is no active reservation on your given name.

USER: It's ok, thank you.

ASSISTANT: Thank you for opting us.