You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, may I know your name?

USER: John Parker here.

ASSISTANT: Yes, John Parker.Which type of help you are seeking from our service?

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

ASSISTANT: Sure, I am happy to help you.

USER: Thank you.

ASSISTANT: There is no reservation on your name to change.

USER: Oh! It's ok, no problem.

ASSISTANT: Ok.

USER: Thank you for your services.

ASSISTANT: My pleasure, hope you have a great day a head.