You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Actually I want to change my existing reservation. Can you help me?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Please share your name.

USER: Sure, I am Betty Young.

ASSISTANT: There is no reservation on your name in our database.

USER: Ok, no problem.

ASSISTANT: Thank you for choosing us.

USER: Thank you for your help.