You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. Can you please tell me how can I guide you?

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

ASSISTANT: Ok, I can help you out. Mean while can you please tell me your name.

USER: Ok. My name is Joseph Hill.

ASSISTANT: Sorry for the inconvenience, no reservation found on your name to change.

USER: Ok, no issues. Thanks for the help.

ASSISTANT: Most welcome.