You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I abet you?

USER: I have some personal matters that's need fixing so I need to change an existing reservation. Can you please help me to change an existing reservation?

ASSISTANT: Sure, may i know your name to check the reservation list and revert you?

USER: My name is Margaret Walker.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: We could not find any reservation by this name in our data base.

USER: That's not a problem. Thanks for your information.

ASSISTANT: Thank you for opting us.