You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. Is there help that you need right now from my side?

USER: Jack Perez here. I would like to change an existing reservation.

ASSISTANT: Yes, I can help you with that flight ticket modification process. Give me a moment to check it.

USER: Sure, take your time.

ASSISTANT: Thank you for your patience, there is no previous flight ticket reservation done for the user name to change it.

USER: No issue, thank you for the help and time.

ASSISTANT: That's my pleasure and thank you for utilising our service to your query.