You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I render you?

USER: I want to change my existing reservation. Could you help me with that?

ASSISTANT: Sure, may I know your good name?

USER: Sarah Davis here.

ASSISTANT: Please wait for a minute, I will revert to you with present status.

USER: Ok.

ASSISTANT: Unfortunately, there is no reservation found  on your name to change.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thanks for approaching us.