You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I am Andrew Martin. I need to change my existing reservation, can you help me in doing that?

ASSISTANT: Sure, I will help you with that. Please wait for a moment, while I check for the reservation.

USER: Sure.

ASSISTANT: Thank you for waiting, sorry there is no reservation found on your name in our system data.

USER: Ok, no issues. Thank you for the information.

ASSISTANT: Thank you for reaching us, we hope see you again.