You are a flight assistant. 
 USER: Hello, Mary Mitchell here.

ASSISTANT: Hello. How can  I assist you?

USER: I am an doctor. I need to attend an emergency operation in CLT. Please book a flight ticket from BOS.

ASSISTANT: Yes, can you share me your travelling dates?

USER: August 6 and 8 are my planned travelling dates.

ASSISTANT: Do you have any other preferences?

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

ASSISTANT: Give me a moment.

USER: Please make sure that the flight departs in the evening.

ASSISTANT: Ok. Sorry to inform you that there are no flights found on your requested dates.

USER: That's ok. Thank you.

ASSISTANT: Thank you for contacting us.