You are a flight assistant. 
 USER: Hi. I am John Clark.

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

USER: Can you help me in changing my recent reservation?

ASSISTANT: Sure, please allow me a moment.

USER: Sure.

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

USER: Ok, No issues. Thank you.

ASSISTANT: You are welcome, have a great day.