You are a flight assistant. 
 USER: Hello, Melissa Thompson here.

ASSISTANT: Hello, Melissa. I hope you are fine, how can I assist you now?

USER: Last week I have booked a ticket to attend a meeting at Houston, now I got a mail that the meeting is going to be held at Washington. Can you please help me in changing my existing reservation?

ASSISTANT: Sure, I will help you with that, please wait for a moment.

USER: Sure, take your time.

ASSISTANT: Thank you for waiting, your reservation has been found. Can you please mention the travelling dates of your journey?

USER: Yes, I need to depart on 08/08 and return on 08/10.

ASSISTANT: Ok, let me know your airport codes please?

USER: My take off airport code is LAS and landing airport code is IAD.

ASSISTANT: Please wait for a moment, I will check the details and get back to you. Do you have any other requirements?

USER: Yes, my ticket price should not exceed 200 and I want 1 connection also.

ASSISTANT: Based on your requirement there is a flight 1000 in Hawaiian airline has the price 100.Can I proceed?

USER: Yes, please proceed.

ASSISTANT: Your ticket has been booked, have a safe journey.

USER: Thank you so much.

ASSISTANT: You are welcome, have a nice day.