You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

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

ASSISTANT: Sure, may I know your name please?

USER: My previous reservation has done with the name Thomas Robinson.

ASSISTANT: Ok, please wait for a moment.

USER: Sure, I will wait for your information.

ASSISTANT: Your reservation found, please share your source and destination airports codes?

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

ASSISTANT: Ok, may I know your travelling dates please?

USER: My planned dates of journey are Nov 22 and Nov 24.

ASSISTANT: Ok, Is there any specific class preference for you?

USER: I prefer business class flight for this trip.

ASSISTANT: Do you have any other specifications please?

USER: I prefer to travel in connecting flight for this trip.

ASSISTANT: Sorry Robinson, there is no flight found as per your travelling details.

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

ASSISTANT: You are welcome.