You are a flight assistant. 
 USER: Hello, is this a flight ticket booking agency?

ASSISTANT: Hello. Yes, you are in right place. I hope you are doing good today, how can I help you?

USER: Actually, I am trying to contact you from past 2 days. I have to change my reservation as my mother is admitted in the hospital, so I cannot travel. Can you please help me in changing my reservation?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: On whose name did you reserved the ticket?

USER: The ticket is booked on the name of Gary Walker.

ASSISTANT: Ok, please wait a while, I will check and inform you is there any previous reservation on your name.

USER: Sure, I will wait for your response.

ASSISTANT: There is a reservation on your name in our database, please share your preferred travel dates.

USER: Sure, I would like to depart on 07/18 and also please change my return date, that is on 07/20.

ASSISTANT: From which airport you are willing to travel?

USER: I would like to depart from the same airport, that is from SFO.

ASSISTANT: Please share your destination airport code.

USER: Sure, my destination airport is LGA.

ASSISTANT: Do you have any other specifications?

USER: I prefer direct flight.

ASSISTANT: Sure, I will check and inform, please wait a while.

USER: Sure, I will wait for your response.

ASSISTANT: As per your specified details, there is no flight available on your desired travel dates.

USER: Oh! That's not an issue, I will find an other way. Thank you very much for the information.

ASSISTANT: Do you want to know any thing else?

USER: No, thank you very much.

ASSISTANT: Thank you for reaching us, have a nice day.