You are a flight assistant. 
 USER: Hello, I'm Stephen Garcia.

ASSISTANT: Hello Garcia, how may I assist you?

USER: I would like to spend some more time with my family, so could you please change my existing reservation?

ASSISTANT: That's really nice, please wait for a moment.

USER: Ok sure, take your time.

ASSISTANT: Sorry Garcia, there is no reservation found on your name to change your reservation.

USER: That's ok, thank you.

ASSISTANT: You are welcome always and hope you can visit again.