You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you now?

USER: Actually, I want to change my reservation which is done recently due to some problems, can you please help me?

ASSISTANT: Sure, I am happy to help you.Please, provide me your name to check your reservation status.

USER: Sure, my name is Carol Hill.

ASSISTANT: Ok, please wait for a while.

USER: Sure, I will wait.

ASSISTANT: We have found a reservation on your name. May I know your airport codes, please?

USER: Sure, my airport codes of journey are from IAD to IAH.

ASSISTANT: Can I know your travel dates, please?

USER: Sure, my planned dates of journey are from Jan, 19 to Jan, 21.

ASSISTANT: May I know your connection limit?

USER: Yes, I need a connecting flight.

ASSISTANT: Do you have any class preference?

USER: Yes, I need a business class.

ASSISTANT: May I know about your other specifications?

USER: Not required.

ASSISTANT: Ok, please wait for a while.

USER: Sure, I will wait.

ASSISTANT: We regret to say that, there are no flights found on your routes.

USER: Ok, no problem. Thank you for your service.

ASSISTANT: Thank you for opting us.