You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: Can you help me to change my existing reservation?

ASSISTANT: Sure, please share your good name?

USER: William Gonzalez here.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no reservation found by your name in our data base.

USER: Ok, not a problem.

ASSISTANT: Thank you for choosing us.

USER: Thank you.