You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Myself Dorothy Clark. Can you help me to change my recent reservation which I did?

ASSISTANT: Sure, I will help you to change your reservation.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your name to change.

USER: Not a problem, thank you.

ASSISTANT: Welcome. Thank you for choosing us.