You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I aid you today?

USER: Can you please help me in changing my existing reservation?

ASSISTANT: Sure, I am here to serve you.

USER: Thank you.

ASSISTANT: May I know your name to modify the reservation?

USER: James Hill here.

ASSISTANT: Ok, please stand by.

USER: Sure.

ASSISTANT: Sorry, there was no reservation found on your name to modify in our portal.

USER: Ok, no worries at all. Thank you.

ASSISTANT: Thank you for contacting us.