You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you today?

USER: I am Sarah Rodriguez, can you help me for changing an existing reservation?

ASSISTANT: Sure, give me a moment. Let me check the database and get back to you.

USER: Ok, I will wait for your response.

ASSISTANT: Sarah Rodriguez, there is no reservation found with your name in our database to change it.

USER: Oh! It's ok, no problem. Thank you for your services.

ASSISTANT: Thank you for contacting us.