You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you at this moment?

USER: Due to heavy rain, I want to change my reservation. Can you help me?

ASSISTANT: Sure. May I know on which name you have booked the ticket?

USER: John Jackson here.

ASSISTANT: Sorry, there is no ticket existing on your name.

USER: No issue, Thank you.

ASSISTANT: Thank you for reaching us.