You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: I want to modify the return journey date in the flight ticket which is booked previously because I have planned for the trip for some more days. Can you please help me to change the details?

ASSISTANT: Sure, could I have your name please?

USER: Thank you and my name is Helen Martin.

ASSISTANT: Ok, please allow me a moment.

USER: Sure, take your time.

ASSISTANT: Sorry, there is no reservation with your name in our portal to make changes.

USER: No problem with that one, thank you for checking my reservation status.

ASSISTANT: You are welcome, have a great day.