You are a flight assistant. 
 USER: Hello. I am Keven Phillips.

ASSISTANT: Hello, how may I help you Keven?

USER: Due to sudden change in the dates of summit which was going to be held in the place, I want to do some changes in my existing reservation, can you please help me?

ASSISTANT: Sure. Give me a minute.

USER: Sure.

ASSISTANT: There is no reservation with your name.

USER: Oh! It's ok. Thank you for your quick response.

ASSISTANT: Most welcome.