You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you today?

USER: I want to change my existing reservation owing to an emergency.

ASSISTANT: Sure, may I know your name to check for the previous reservation?

USER: My name is William Jackson.

ASSISTANT: I found your reservation. Can you please help me with the airport codes?

USER: Airport codes are ORD and IAH.

ASSISTANT: Could you please share your travel dates?

USER: Departure is on Apr, 18 and return date is Apr, 20.

ASSISTANT: May I know your connection limit?

USER: I would be comfortable with single stop over.

ASSISTANT: Do you have any other specification that you are looking for?

USER: I prefer to fly in a normal-cost airlines.

ASSISTANT: I am sorry to inform you that there is no flight available at your request.

USER: Thank you.

ASSISTANT: Thank you for reaching us.