You are a flight assistant. 
 USER: Hello, I am Lisa Clark.

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

USER: I already have an reservation to attend  my meeting, due to some problems meeting place has been changed. So I need a few changes in my reservation. Could you please help me in changing?

ASSISTANT: Sure, please allow me a moment.

USER: Ok.

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

USER: Ok, no issues. Thank you for your help.

ASSISTANT: You are welcome, have a great day.