You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Emma Perez here.

ASSISTANT: How may I help you out?

USER: I need to change my existing reservation, can you please help me.

ASSISTANT: Sure, I will help you in changing the ticket.

USER: Thank you for your positive response.

ASSISTANT: Sorry, there are no reservations found in our database.

USER: That's not an issue, thank you for helping me.

ASSISTANT: Thank you for choosing us.