You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I want to change my existing reservation. Could you help with that?

ASSISTANT: May I know your name?

USER: John Hernandez here.

ASSISTANT: I have found your reservation, can you please let me know your new travelling airport codes?

USER: My travelling airport codes are from SEA to LAS.

ASSISTANT: Can I know your new travelling dates?

USER: My travelling dates are from Mar 06-08.

ASSISTANT: May I know your class preference?

USER: I prefer for economy class.

ASSISTANT: Do you need any connecting flight for your journey?

USER: I need connecting flight.

ASSISTANT: Here is a connecting flight with fare 200 and 1001 as flight number. Shall I proceed to alter your ticket?

USER: Yes, please proceed.

ASSISTANT: Ok, your ticket is altered to economy class.

USER: Thank you.

ASSISTANT: Thank you for reaching us.