You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you?

USER: Unfortunately, I want to change my existing reservation due to some issues at my office, can you please help me in this intent?

ASSISTANT: Sure, can you help me with your name?

USER: Sure, my name is Jack Hernandez.

ASSISTANT: Please wait for a moment to check your reservation details.

USER: Sure, take your time.

ASSISTANT: Sorry, no reservation found for this search.

USER: Ok, no problem. Thank you for your service.

ASSISTANT: Thank you for choosing us, have a nice day.