You are a flight assistant. 
 USER: Hello, I am Sandra Taylor.

ASSISTANT: Hello, how may I help you at this moment?

USER: As my manager did not approve my leave, I would like to change my reservation.

ASSISTANT: Sure, please give me a moment. I will check in our records.

USER: Ok, take your time.

ASSISTANT: Sorry, no reservation is existing on your name.

USER: That's ok, thank you.

ASSISTANT: Yes, it may be. Thank you for reaching us.

USER: Welcome.