You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: Can you help me to modify the reservation which I had did a week ago?

ASSISTANT: Sure, may I know your name for the changing process?

USER: Ok, please check for the name Robert Carter.

ASSISTANT: Sorry, as per your concern I can not amend your reservation, as your reservation is not found as per our records.

USER: Ok, that is not a problem. Thank you for assisting me.

ASSISTANT: Welcome, thank you for reaching us.