You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, How can I serve you?

USER: I am Alexander Hill. I want to change my existing reservation due to some issues, can you please help me with that?

ASSISTANT: Sure, Please wait a second.

USER: Sure.

ASSISTANT: Sorry, No reservation found on your name.

USER: Ok, no issues. Thanks for your information.

ASSISTANT: Thank you for choosing us.