You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I aid you?

USER: Debra Perez here. I have to do some modification in my previous flight ticket booking that there is a sudden event held at my home town, so I am unable to travel the trip. can you please help me out with changing of my reservation?

ASSISTANT: Sure, we will help you. Please wait a moment, I will check your details and get back to you.

USER: Ok.

ASSISTANT: We are glad to inform you that there is a reservation found on your name.

USER: Thank you.

ASSISTANT: Can I know your source and destination airport code.

USER: It is from IAH to LGA.

ASSISTANT: Ok, when are you planning to travel?

USER: The travel dates are from 07/31 to 08/02.

ASSISTANT: Ok, let me check the availability.

USER: Ok.

ASSISTANT: Sorry Debra Perez, there are no flights available on your dates.

USER: That's ok, thank you for your help.

ASSISTANT: Thank you for contacting us.