You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: David Perez here. I was made a reservation earlier in this week. But I want to change my reservation. Can you please help me for that?

ASSISTANT: Sure, I will help you out.

USER: Thank you for that.

ASSISTANT: Please wait a moment. I will check the status.

USER: Ok, I will wait.

ASSISTANT: Sorry, there are no reservations found.

USER: Anyway, thank you for the information.

ASSISTANT: Thank you for choosing us.