You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Nancy White here.

ASSISTANT: How can I help you today?

USER: Can you please help me with changing my reservation?

ASSISTANT: Sure, I am glad to help you with that.

USER: Thank you for your positive response.

ASSISTANT: I found your reservation, may I know your new travelling airport codes?

USER: My airport codes are from DFW - LAX.

ASSISTANT: On which dates you want me to book your tickets?

USER: My journey dates are from Aug 12th to Aug 14th.

ASSISTANT: Do you have any specifications?

USER: I need a business class reservation only.

ASSISTANT: Please wait a moment.

USER: Sure, please check for 1 connection flight.

ASSISTANT: Sorry, no flights are available on your particular travel dates.

USER: Oh! That's really disappointing to know. Anyways, thank you for checking.

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

USER: Most welcome.