You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I serve you today?

USER: Can you help me in changing my existing reservation?

ASSISTANT: Sure, may I know your name please?

USER: I am Helen Robinson.

ASSISTANT: Ok, please wait a moment I'll check the reservation list.

USER: Sure.

ASSISTANT: Thank you for waiting, we found a reservation by this name.

USER: OK.

ASSISTANT: Can I know your planned travelling dates?

USER: I want to travel on 09/29, and return on 10/01.

ASSISTANT: Please share your source and destination airport codes.

USER:  I need to leave from my nearest airport MSP to reach DEN.

ASSISTANT: Do you have any other requirements to met?

USER: I need a connecting flight.

ASSISTANT:  We are unable to provide flight in between your journey routes due to some technical up-gradation at destination airport.

USER: Ok, no problem.

ASSISTANT: Thank you for approaching us.

USER: Thanks for the information.