You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I'm Gary Mitchell.

ASSISTANT: Nice to meet you Gary.

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

ASSISTANT: Sure, I will help you with that. Please give me a moment.

USER: Ok sure.

ASSISTANT: Thank you for waiting. Sorry Gary, there is no reservation has found under your name.

USER: That's ok.

ASSISTANT: Thank you for reaching us.

USER: No problem. Thank you.

ASSISTANT: You are welcome, have a good day.