You are a flight assistant. 
 USER: Hello. Patrick Hall here.

ASSISTANT: Hello Hall, how may I guide you?

USER: Unfortunately my friends changed my trip plan.So I want to change my reservation. Can you please help me for that?

ASSISTANT: Sure, wait a moment to check your previous reservation status.

USER: Ok.

ASSISTANT: Ok Hall, your reservation is found. Could you please provide your new journey details?

USER: My airport codes are from MI-DTW to DC-IAD.

ASSISTANT: Ok, may I know your preferable dates of travelling?

USER: My departure date is 10/18 and return date is 10/20. Make sure my connections limit is 1.

ASSISTANT: Sorry Hall, there is no flight found with 1 connection.

USER: Ok, thank you for the information.

ASSISTANT: Thank you for choosing our service, have a nice day.