You are a flight assistant. 
 USER: Hello, I am Robert Lopez.

ASSISTANT: Hello, how can I assist you?

USER: As I am a doctor having an emergency work in hospital.So, can you please change my existing reservation?

ASSISTANT: Please wait for a while, I will check and revert you.

USER: Sure.

ASSISTANT: Sorry there is no reservation found on your name.

USER: It's ok thanks for the information.

ASSISTANT: Thank you for reaching us, have a nice day.