You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: Please assist me to change my existing reservation.

ASSISTANT: May I know your name please to check the status of your reservation?

USER: I am Patricia Carter.

ASSISTANT: Thank you. Please stay online for a while, I will check your reservation status and let you know.

USER: Sure, take your time.

ASSISTANT: Sorry, there is no reservation matching with your name in our portal to make changes further.

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

ASSISTANT: Thank you for reaching us.