You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: George Taylor, here.

ASSISTANT: How may I help you? Yes, George.

USER: There is change in dates of my meeting with client, so I want to change my existing reservation.

ASSISTANT: Ok, let me check with your details.

USER: Sure.

ASSISTANT: Sorry to say George, I didn't found any reservation under your name.

USER: It's ok, thanks for helping me.

ASSISTANT: Thank you for reaching us.