You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you at this moment?

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

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Please check on the name of Jacob Roberts.

ASSISTANT: We found a reservation on your name, can you please forward your journey dates?

USER: My new journey dates are July 19 and July 21.

ASSISTANT: Kindly assign your airport codes?

USER: Airport codes are from DEN to CLT.

ASSISTANT: Do you prefer any stopover in between journey?

USER: I require a stopover.

ASSISTANT: Is there any more specifications in your journey?

USER: I would like to depart in the afternoon and return in the evening.

ASSISTANT: Sorry, we did not find any flights matching your details.

USER: It's ok, thank you for checking.

ASSISTANT: Thank you for choosing us.