You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, may I know how best I can help you today?

USER: I made a reservation earlier to go for a holiday trip with my friends, due to some financial problems I want to change my existing reservation. Can you help me out?

ASSISTANT: Sure, we are here to fulfil your request.

USER: Thank you.

ASSISTANT: May I know your name to find your recent reservation?

USER: Sure, Justin Walker is my name.

ASSISTANT: Sorry, we did not find any reservation on your name to change.

USER: Thank you for quick response.

ASSISTANT: Thank you for making us to serve you today.