You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what can I do for you today?

USER: I want to change my existing reservation due to sudden postpone of my exams dates. Can you help me with that?

ASSISTANT: Sure, can you please share your name to proceed further?

USER: I am Lisa Roberts.

ASSISTANT: Sorry, no reservation found with your name in our portal to change it.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for reaching us.