You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I address you?

USER: I want to change my existing reservation, can you help me out?

ASSISTANT: Sure, may I know your name?

USER: Sure, Timothy Parker here.

ASSISTANT: Ok, please wait.

USER: Sure.

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

USER: Ok, no worries at all. Thank you.

ASSISTANT: Thank you for choosing us.