You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Jennifer Garcia.

ASSISTANT: How may I assist you?

USER: As my meeting got postponed at Dallas, can you please help me in changing my existing reservation to Dallas?

ASSISTANT: Sure, I will help you with the change of flight reservation.

USER: Thank you.

ASSISTANT: Please wait for a moment.

USER: Sure, I will wait for your response.

ASSISTANT: I have found your flight reservation. Please tell me your airport codes?

USER: My nearest airport codes of journey are from MCO to ORD.

ASSISTANT: Now help me with your travel dates please?

USER: My preferable journey dates are from 07/22 to 07/24.

ASSISTANT: Thanks for waiting. But I am sorry to say that presently there are no flights available.

USER: Ok, not an issue. Thank you for providing information.

ASSISTANT: Thank you.