You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. What can I do for you?

USER: I am Stephanie Allen. 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, please wait a moment.

USER: Ok, take your own time.

ASSISTANT: Sorry, no reservation has been found on your name.

USER: It's ok, no problem.

ASSISTANT: Thank you for choosing us.

USER: Thank you for your help.