You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am John Scott.

ASSISTANT: How can I help you today?

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

ASSISTANT: Sure, I can help you with that.

USER: Thank you.

ASSISTANT: Ok, please wait a moment.

USER: Ok.

ASSISTANT: There is no previous reservation available on your name John Scott.

USER: Oh! I think my sister's already changed my reservation. Anyway thank you for your services.

ASSISTANT: Thank you for reaching us, have a good day.