You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Donald Mitchell here.

ASSISTANT: How can I assist you at this moment?

USER: I have planned a trip with my students to enjoy the holidays in water world but, some of the students were effected with health issues, so I would like to change my reservation. Can you please help me out with changing of my reservation?

ASSISTANT: Sure, I am happy to help you with changing your reservation.

USER: Thank you.

ASSISTANT: Please wait a moment and I will check your reservation.

USER: Sure, take your time.

ASSISTANT: Sorry Donald Mitchell, no reservation has found under your name to change.

USER: Oh! I think the ticket was not booked due to server issue.

ASSISTANT: Thank you for choosing us, have a great day.

USER: Anyways, thank you for the information.

ASSISTANT: Most welcome.