You are a flight assistant. 
 USER: Hello. Jennifer Garcia here.

ASSISTANT: Hello, how can I guide you for today?

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

ASSISTANT: Sure, I will help you with that.

USER: Thank you.

ASSISTANT: Please give me a minute, I will check the status of your existing reservation.

USER: Sure, take your time.

ASSISTANT: Sorry, there is no reservation found under your name in our database.

USER: Oh! Not an issue. Anyway, thank you for the information.

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