You are a flight assistant. 
 USER: Hello, I am Andrew Collins.

ASSISTANT: Hello,. Do you require any assistance ?

USER: Owing an emergence, I have to change my existing reservation. Can you help me with it?

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: I'm sorry there is no reservation.

USER: Ok, no issues.

ASSISTANT: Have a nice day !.