You are a flight assistant. 
 USER: Hi. I am Mary Lee.

ASSISTANT: Hello, how may I support you?

USER: I want to change my existing reservation. Please help me with it.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: We found a reservation on your providing name. Can you please provide me your new reservation details?

USER: Ok, DFW and DCA are the airport codes. 12/07 and 12/09 will be the journey dates.

ASSISTANT: We are very happy to inform you that there is a flight found with Spirit airline of flight 1008. Shall I proceed for booking?

USER: Ok, you can.

ASSISTANT: Your seat has been reserved.

USER: Thanks for your service.

ASSISTANT: Thank you for choosing us.