You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I am Anna Lopez from Detriot. I want to change my travel dates in my previous reservation, can you help me with that?

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, no reservation found on your name. Thank you for reaching us, have a nice day.

USER: Oh! It's ok no problem. may be I am not booked my ticket properly at that time. Thank you for your service.

ASSISTANT: Welcome.