You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am David Miller.

ASSISTANT: How may I assist you David?

USER: I gave wrong airport codes in my previous reservation, so can you help me for changing an existing reservation?

ASSISTANT: Sure, I will be helping you with it.

USER: Thank you.

ASSISTANT: Please give me a moment, and I will revert back to you with the information.

USER: Ok, I will wait for your response.

ASSISTANT: Sorry to tell you David Miller, but no reservation is found by your name.

USER: Oh! I think my friend already changed my reservation.

ASSISTANT: Thank you for choosing our agency, keep reaching us for your further bookings.

USER: Thank you for your support.

ASSISTANT: Have a nice day.