You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist  you now?

USER: Due to sudden change in my trip to another location, I would like to do some changes in existing my reservation. Can you please help me out?

ASSISTANT: Sure, can I have your good name please?

USER: Jennifer White here.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Sorry to inform you that  no reservation has found under your name to change.

USER: That's ok, thank you.

ASSISTANT: Thank you for choosing us.