You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you now?

USER: I would like extend my vacation for some more days. So, can you help me in changing my existing reservation?

ASSISTANT: Sure, can I know your name please?

USER: My name is Rebecca Perez.

ASSISTANT: Sorry Perez, there is no reservation found on your name.

USER: That's fine, thank you for the information.

ASSISTANT: Thank you for your positive response.

USER: Welcome.