You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: Due to sudden change in my trip to another location, I would like to do some changes in existing my reservation. Can you please help me out?

ASSISTANT: Please provide your name?

USER: Margaret Davis here.

ASSISTANT: Sorry, there is no reservation by your name.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you.