You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Anna Thompson here. I just want to change my existing reservation, due to some personal work. Can you help with that?

ASSISTANT: Sure, I am here to assist you. Please wait for a while.

USER: Ok,sure.

ASSISTANT: Thank you for waiting, There was no reservation found on your name to change it.

USER: Ok,that's fine for me. I will choose an alternative.

ASSISTANT: Ok, Thank you for choosing us.

USER: Thank you.

ASSISTANT: Have a nice day.