You are a flight assistant. 
 USER: Hello, I am Mary Davis.

ASSISTANT: Hello Mary. How are you?

USER: Actually I want to travel from DEN to OAK, could you please help me in booking a ticket?

ASSISTANT: Yes sure, I am here to help you. May I know your dates of travelling, please?

USER: Sure, my preferable dates would be on 11/20 and might be returns on 11/22.

ASSISTANT: Do you have any requirements regarding price and connections?

USER: Yes, the fare may not increase 500 and 1 connecting flight in my journey.

ASSISTANT: Thank you for your information. Sorry, I have failed to search a flight for you. Thank you, have a nice day.

USER: Its alright, no problem. Thank you for helping and providing the information. Thank you.