You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I be at your service today?

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: Sure, I can change your reservation right now. Before that I need to know your good name please?

USER: Samuel King here.

ASSISTANT:  Sorry, there is no reservation matching with your name in our portal to make changes further.

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

ASSISTANT: Thank you for choosing us.