You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: Owning to an emergency, I want to change my existing reservation. Can you help me?

ASSISTANT: Sure, please share your name.

USER: Yes, I am Christine Turner.

ASSISTANT: Reservation found. May I know your travelling dates?

USER: Ok, my planned trip dates are on Feb 03 and return on Feb 05.

ASSISTANT: May I know your airport codes?

USER: Ok, my airport codes are from Boston BOS to SFO.

ASSISTANT: Do you have any connection limit?

USER: Yes, I need a single connecting flight.

ASSISTANT: May I know your preferable timings?

USER: No, I don't have any timings.

ASSISTANT: Do you have any requirements?

USER: ok, I need a normal cost.

ASSISTANT: There are no flights available on your required routes.

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

ASSISTANT: Thank you for choosing us.