You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you today?

USER: I need to travel from SFO to OAK. Can you please book a direct flight for me?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: On which dates do you like to travel?

USER: I want to travel on Sept 8 and need to return on Sept 10.

ASSISTANT: Is there any class preferences to be met?

USER: Yes, I prefer an economy class for this trip.

ASSISTANT: On which name do you like to reserve this ticket?

USER: Please book a flight under the name of Sandra Johnson.

ASSISTANT: Do you prefer any other specification?

USER: Yes, I would like to travel in normal-cost airline.

ASSISTANT: Sorry, there is no flight available on your travel dates.

USER: Ok, no problem. Thank you for the information.

ASSISTANT: Thank you for choosing us.