You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I want to change my destination airport code in my existing reservation, can you please help me out?

ASSISTANT: Sure, may I know your name?

USER: Sure, my name is Patricia Hernandez.

ASSISTANT: Wait a minute.

USER: Ok, take your time.

ASSISTANT: We found your reservation, can you please let me know your airport codes?

USER: Sure, my airport codes are DEN and AUS.

ASSISTANT: When are you going to travel?

USER: Ok, my travelling dates are Dec 03 and Dec 05.

ASSISTANT: Can I know your specifications?

USER: I don't have any other specifications.

ASSISTANT: Wait a minute.

USER: Ok, take your time.

ASSISTANT: Sorry, there are no flights available on your travelling dates.

USER: It's ok, thank you for the information.

ASSISTANT: Thank you for choosing us.