You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you today?

USER: Can you please change my existing reservation?

ASSISTANT: Sure, may I know your name?

USER: I am Mary King.

ASSISTANT: Please wait for a minute.

USER: Sure.

ASSISTANT: We found a reservation on your name, may I know your trip dates?

USER: Sure, my travel dates are 05/21 and 05/23.

ASSISTANT: Kindly provide your boarding and landing points.

USER: My airport codes are from LGA to SEA.

ASSISTANT: Do you have any other requirements?

USER: I need a connecting flight.

ASSISTANT: Please wait for a minute.

USER: Sure.

ASSISTANT: Sorry, there were no flights found on your route to change.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for contacting us.