You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I am Catherine Garcia. I want to change my reservation, can you help me to modify my reservation?

ASSISTANT: Sure, we are here to serve you. Please hold a moment, let me check your reservation and let you know.

USER: Sure.

ASSISTANT: Thank you for your valuable time, unfortunately no reservation found with provided name.

USER: Ok, thanks for informing me.

ASSISTANT: Thank you for availing us.