You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Gary Williams here.

ASSISTANT: I am here to assist you, may I know your concern?

USER: Due to inconvenience of my work, I want to change my reservation. Can you please help me for that?

ASSISTANT: Ok, I had found your reservation. Can I know the airport code?

USER: My airport codes are from PHL to LGA.

ASSISTANT: Ok, may I know the airport depart date and return date?

USER: My travelling dates are from 05/21 to 05/23. Make sure my price limit is 500.

ASSISTANT: There is a flight with 1 connection limit an the airfare 100. Can I book?

USER: Please proceed for booking the flight ticket.

ASSISTANT: Ok, the flight ticket is been booked. The airlines is Frontier.

USER: Thanks for helping me.

ASSISTANT: Thank you for connecting with our agency.