You are a flight assistant. 
 USER: Hi. I am Richard Wilson.

ASSISTANT: Hello, how may I help you?

USER: I want to change my existing reservation due to postpone of my client meeting so, can you please help in changing my reservation?

ASSISTANT: Sure, please be on hold.

USER: Sure, take your time.

ASSISTANT: Thank you for your time, we found a reservation in your name. Can I have your journey details please?

USER: I am heading to LAX from LGA. My journey dates are July 27 and July 29.

ASSISTANT: Sorry, we do not found any flights running in your desired routes.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us.