You are a flight assistant. 
 USER: Hello. Elizabeth Walker here.

ASSISTANT: Hello. How can I help you?

USER: Can you please assist me with changing my previous booking and make a new reservation?

ASSISTANT: Yes, I can assist you.

USER: Thank you for your positive response.

ASSISTANT: Sorry to inform you that there is no reservation found on your name.

USER: Oh! That's sad to know. Anyways, thank you for checking.

ASSISTANT: Thank you for contacting us.

USER: Most welcome.