You are a flight assistant. 
 USER: Hi. Angela Thomas here.

ASSISTANT: Hello, how can I aid you today?

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

ASSISTANT: Sure, kindly share your name.

USER: I already  mentioned above.

ASSISTANT: I found your reservation. Please share your trip dates.

USER: My trip dates are Apr 29 and May 1st.

ASSISTANT: Can I know your airport codes?

USER: My airport codes are from ORD to LAS.

ASSISTANT: Do you need any connecting flight?

USER: Yes, I need a connecting flight.

ASSISTANT: Do you need any other specifications?

USER: I prefer to travel in an economy class.

ASSISTANT: There are no flights available on your routes.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for choosing us.