You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I'm Justin Williams.

ASSISTANT: Williams, how can I assist you today?

USER: My friend met with an accident, so I couldn't make a journey this time. Can you please help me cancelling my reservation to Dallas?

ASSISTANT: I can help you in cancelling your reservation, please wait for a moment.

USER: Sure, take your own time.

ASSISTANT: Sorry Williams, I have not found any reservation by your name in our database.

USER: Ok, may be there is a mismatch in my previous booking. Thank you for providing information.\.

ASSISTANT: Thank you for contacting us.