You are a flight assistant. 
 USER: Hi. Karen Hernandez here.

ASSISTANT: Hello, how can I assist you?

USER: Can you please reserve me a flight ticket from SFO to DFW?

ASSISTANT: Sure, can you provide your trip dates?

USER: My trip dates are 05/28 - 05/30.

ASSISTANT: Do you have any preferences?

USER: I need a business class.

ASSISTANT: Give me a minute.

USER: Sure.

ASSISTANT: Sorry, there is no flight on your given preferences.

USER: No issues, thank you.

ASSISTANT: Thank you for choosing us.