You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Alexander Roberts here.

ASSISTANT: How can I help you today?

USER: I am looking for a normal-cost airline to visit Philadelphia. Can you book the flight ticket?

ASSISTANT: Sure, we are here to help you. Please let me know your planned travelling dates.

USER: The travel dates are from 25 Apr to 27 Apr.

ASSISTANT: Could you please share your take off and landing airport codes?

USER: The airport codes are from OAK to PHL.

ASSISTANT: May I know if you prefer to have any other comforts in your journey?

USER: I need a single connecting flight.

ASSISTANT: Can I know your depart and arrival timings?

USER: The return time would be morning.

ASSISTANT: Ok, please wait a moment.

USER: Sure.

ASSISTANT: Thank you for waiting,  we are unable to provide flight in between your journey routes due to some technical up-gradation at destination airport.

USER: Not a problem.

ASSISTANT: Thank you for choosing us.

USER: Thank you.