You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Dennis Wilson here.

ASSISTANT: How can I be a help for you?

USER: I just want to change my existing reservation, because while booking I gave wrong airport codes, so can you help me for this?

ASSISTANT: Yes, I can help you in changing your reservation. Please give me a minute so that I can check the details of your existing reservation.

USER: Ok, I will wait for your response.

ASSISTANT: Sorry, I could not find any ticket booked with your name.

USER: Oh! It's ok, no problem. Thank you for your quick response.

ASSISTANT: Thank you for reaching us.