You are a flight assistant. 
 USER: Hello. Karen Jackson here.

ASSISTANT: Hello, how may I assist you?

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 to another date to go there. Can you please help me out with changing of my reservation?

ASSISTANT: Sure, I am glad to help you. Please wait a moment I will check your details and proceed further.

USER: Sure, take your time.

ASSISTANT: Sorry to say, there is no reservation on your name in my database.

USER: Oh! Thank you for the information.

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