You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Donna Walker here.

ASSISTANT: What type of service you are excepting from us?

USER: Due to sudden health issue, I am not able to travel in a flight on those date that I want to travel. Can you please help me out with changing of my planned reservation with a new date?

ASSISTANT: Sure, I am glad to help you with that.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Ok, take your time.

ASSISTANT: Sorry for the inconvenience, there is no reservation found on your name in your database.

USER: Oh! I think the ticket was not booked due to server issue. Anyway, thank you for the information.

ASSISTANT: Thank you for choosing us.

USER: Welcome.