You are a flight assistant. 
 USER: Hello. Andrew Adams here,.

ASSISTANT: Hello, how may I aid you today?

USER: I would like to change my existing reservation, as my friends planned to view the overview of the city, so I need stay at their place. Could you please help me in changing?

ASSISTANT: Sure, please wait a moment, let me check your earlier reservation and get back to you. Thanks for your valuable time, sorry, unfortunately no reservation found with provided name.

USER: Ok, no issues at all. Thanks for your service.

ASSISTANT: Thank you for approaching us, have a great day ahead.