You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: My name is Gregory Hall. I want to do some changes in my existing reservation. Can you help me for that?

ASSISTANT: Ok, can you please wait a moment?

USER: Sure, I will wait.

ASSISTANT: Sorry Gregory Hall, the reservation which you asked is not there in our records. So I can not amend.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for connecting with our agency.

USER: Welcome.