You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how could I aid you today?

USER: I am Gregory Taylor. I want to change my existing reservation. Could you help me with that?

ASSISTANT: Sure, please wait for some time.

USER: Ok.

ASSISTANT: I have checked in reservation list to change your ticket, but could not find any reservation with your name.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.