You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: I am Rebecca Wright. Due to some entrepreneurship meeting, I am going to change my existing reservation. Can you please help me in changing the reservation?

ASSISTANT: Rebecca Wright, I am glad you have contacted us. I will help you.

USER: Thank you.

ASSISTANT: Please allow me a minute. Please help me with your planned travelling dates.

USER: I will start on 01/18 and return on 01/20.

ASSISTANT: Thank you. Please let me know with your depart and return airport codes.

USER: My travelling airport codes are EWR to SFO?

ASSISTANT: Do you need a break in your journey?

USER: I need a break in my journey.

ASSISTANT: Do you have any other preferences in your journey?

USER: I want to return in the morning time.

ASSISTANT: Please let me know if you have any other preferences in your journey.

USER: I prefer for economy class.

ASSISTANT: Rebecca Wright, I am really sorry to inform you that there are no flights available for your journey.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us. Have a great time.