You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: I need to change my recent existing reservation due to postpone of my document verification in office. Will you help me with that?

ASSISTANT: Sure, we will help you.

USER: Thank you for accepting my request.

ASSISTANT: May I know your name?

USER: Myself Sandra Allen.

ASSISTANT: We found a reservation on your name, can you please help me with your travel dates?

USER: My travelling dates are Mar 20 and Mar 22.

ASSISTANT: May I know your airport codes?

USER: My airport codes are PHX and DEN?

ASSISTANT: Do you have any connection limit?

USER: I need a connecting flight.

ASSISTANT: Is there any airline preference?

USER: No, I don't have any specifications.

ASSISTANT: We found an airline Frontier with flight 1007 having a fare 200 with stopover. Shall I change your reservation?

USER: Sure, you can proceed.

ASSISTANT: Your reservation has been changed successfully.

USER: Thank you for helping me.

ASSISTANT: Thank you for reaching us.