You are a flight assistant. 
 USER: Hello. I am David Clark.

ASSISTANT: Hello, How may I serve you?

USER: Meeting my friend has been canceled, help me in cancelling my resent reservation.

ASSISTANT: Sure, I am happy to serve you. Please wait for a moment, I will let you know.

USER: Sure.

ASSISTANT: Thanks for waiting. We apologise that, we did not find any reservation with your name in the reservation list.

USER: Alright, thank you for your fast response.

ASSISTANT: Thank you for contacting us.