You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I want to change an existing reservation, so please help me in the cancellation.

ASSISTANT: Ok, may I know your name to check your reservation?

USER: Myself Gregory Hill.

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

USER: Not an issue. Thank you.

ASSISTANT: Thanks for contacting us.