You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you at this moment?

USER: I want to change my existing reservation to new travel dates, can you help me over that?

ASSISTANT: Sure, I will help you to change that reservation but I need your name to check details.

USER: Sure, I am Thomas Hall.

ASSISTANT: Please wait for a minute.

USER: Ok, take your time.

ASSISTANT: Based on your request, I could not find any reservation with your name to change that reservation.

USER: It's ok, it might be not done properly while booking.

ASSISTANT: It's my pleasure, have a safe journey.