You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, welcome to Global Booking Agency. How may I assist you today?

USER: I have planned to go for IAH from LGA unfortunately my meeting got postponed, can you please change my existing reservation?

ASSISTANT: Sure, can I have your name to check your details?

USER: Myself Helen Smith.

ASSISTANT: Helen, please be on hold for a moment to check and modify it. Sorry Helen, there is no active reservation under your name to modify.

USER: Ok. Thank you for your information.

ASSISTANT: You are welcome. Thank you for reaching us, have a good day.