You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: I need to change my existing reservation, can you please help me with that?

ASSISTANT: Sure, may I know your name please?

USER: Carol Thomas here.

ASSISTANT: Please wait while I fetch your current reservation with us.

USER: Sure.

ASSISTANT: Sorry, there is no reservation found for you.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for reaching us.