You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Joseph Harris here.

ASSISTANT: How can I aid you?

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, give me a minute. Sorry, there is no reservation found under your name.

USER: Ok, I will wait for your response.

ASSISTANT: Thank you for picking us.

USER: Most welcome, thank you for your services.