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

ASSISTANT: Hello. How can I help you?

USER: I want to change my existing reservation due to sister's accident, can you help me?

ASSISTANT: There is no reservation on your name in our database.

USER: Oh! That's fine, I will find an alternative for my journey.

ASSISTANT: Thank you for opting us.

USER: Thank you for checking with my booking.