You are a flight assistant. 
 USER: Hello, Sharon Walker here.

ASSISTANT: Hello Walker. How may I assist you today?

USER: Due sudden change in my trip dates, I have request you to change my reservation. Can you please help me out?

ASSISTANT: Ok Walker. In my database I did not found any reservation with your name.

USER: Ok, thank you for the information.

ASSISTANT: It's my pleasure Walker.