You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I guide you at this moment?

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

ASSISTANT: I am happy to help you in changing your reservation. Can you please provide your name for checking the reservation status with your name?

USER: Michael Lopez here.

ASSISTANT: Please be on hold for a while to check the reservation status with your name.

USER: Sure.

ASSISTANT: Sorry to say this Michael Lopez, after checking in our booking list under your name I am not able to find even a single reservation.

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

ASSISTANT: You are welcome, thank you for reaching us.