You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you for today?

USER: I want to change my reservation, can you please help me to change my reservation?

ASSISTANT: I am glad to help you in changing your reservation. Can you please provide your name in checking your reservation status?

USER: Sure, my name is Charles Miller.

ASSISTANT: Sorry for the trouble which is caused to you, I have not found any reservation on your name in our database.

USER: Ok, not an issue, thank you for checking my reservation status.

ASSISTANT: You are welcome, thank you for reaching us. Hope you have a nice day ahead.