You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Matthew Hernandez.

ASSISTANT: How may I guide you?

USER: i need to change my existing reservation, can you please help me with that?

ASSISTANT: Hernandez, I am willing to help you with this. Let me check your reservation status in our database.

USER: Ok.

ASSISTANT: Hernandez sorry to intimate, no reservation is available with your criteria.

USER:  Ok, no problem. Thanks for your information.

ASSISTANT: Thank you Hernandez for utilizing our agency.