You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: help me to change my existing reservation due to sudden changes in my journey dates.

ASSISTANT: Ok, may I know your good name please?

USER: I am Frank Thompson.

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: Thanks for waiting, no reservation found with your name to change.

USER: Ok, no problem. Thank you.

ASSISTANT: Thanks for availing us.