You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: Mary Parker here. Due to inconvenience of my work, I want to change my reservation. Can you please help me for that?

ASSISTANT: Sure, please wait a moment I will check your details and proceed further.

USER: Ok, I will wait.

ASSISTANT: I am happy to say that I found a reservation on your name. Could you please provide your new airport codes?

USER: My departure date is 11/22 and return date is 11/24. My airport codes are from DFW and SFO.

ASSISTANT: Ok, please wait a moment.

USER: Ok, I will wait.

ASSISTANT: Sorry to say, no flights were available on your dates.

USER: Anyway, thanks for the information.

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