You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: I am Sandra Moore. I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, give me a minute for checking.

USER: Sure.

ASSISTANT: Sorry, there is no active reservation found under your name.

USER: Ok, no problem.

ASSISTANT: Thank you for reaching us.

USER: Thanks for your information.