You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Andrew Carter.

ASSISTANT: Carter, how can I help you today?

USER: I want to change my previous source and destination codes. Can you please help me out in changing my existing reservation?

ASSISTANT: Sure, I will help you with that. Please wait for a moment.

USER: Sure, I will wait for your response.

ASSISTANT: Carter, I did not found any reservation under your name.

USER: Ok, no problem. Anyway, thank you for the information.

ASSISTANT: Thank you for choosing us.