You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you today?

USER: Can you please help me to change my travelling dates on existing reservation?

ASSISTANT: Sure, I will help you with that. Can you please provide your name to check your previous reservation status?

USER: My name is Jack Moore.

ASSISTANT: I have found reservation on your name, can you please provide your new preferable travelling dates?

USER: My travelling dates are on Aug 04 and Aug 06.

ASSISTANT: Ok, may I know your origin and destination airport codes for booking?

USER: My origin point is DEN and destination point is PHX.

ASSISTANT: Do you have any connection limit?

USER: I need only single connection.

ASSISTANT: Any other preferences do you have?

USER: I want to depart in the afternoon time.

ASSISTANT: Please wait a moment to check the flights.

USER: Sure.

ASSISTANT: Unfortunately there are no flights running on your route with your required preferences.

USER: Ok, thanks for notifying me.

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