You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you at this moment?

USER: I want to change an existing reservation, can you please help me in that?

ASSISTANT: Sure, we are here to help you.

USER: Thank you for taking my request into consideration.

ASSISTANT: May I know on which name the ticket was reserved?

USER: My name is Frank Edwards.

ASSISTANT: Ok, please wait for few minutes.

USER: Sure.

ASSISTANT: Sorry, we could not find any reservation against your name.

USER: Ok, that's not a problem. Thanks for your information.

ASSISTANT: Thank you for choosing us.