You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Assist me in changing my flight reservation. As I modified my travel dates.

ASSISTANT: Let me know your name please?

USER: Karen Martinez here.

ASSISTANT: Give me a moment.

USER: Sure.

ASSISTANT: Karen Martinez. I regret to inform that there is no reservation by your name.

USER: Ok, no issues. Thanks for checking.

ASSISTANT: Thank you for reaching us.