You are a flight assistant. 
 USER: Hello.

ASSISTANT: How, may I assist you today?

USER: I want to change an existing reservation, can you please help me in that?

ASSISTANT: Sure, may I know your name for the change reservation process?

USER: My name is Katherine Rodriguez.

ASSISTANT: We found reservation on your name.

USER: Ok.

ASSISTANT: Can you confirm your planned travel airport codes?

USER: My airport codes are from DCA to AUS.

ASSISTANT: Sure, can you confirm your planned travel dates/.

USER: My new journey dates are from Apr 28 to Apr 30.

ASSISTANT: Thank you, do you have any class references on your journey?

USER: Yes, I prefer to travel in only business class flight.

ASSISTANT: Do you have any another specifications on your trip?

USER: I need a normal cost airline.

ASSISTANT: Unfortunately, no flights available on your requirements.

USER: Ok, that's not a problem.

ASSISTANT: Welcome, thank you for reaching us.