You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Frank Perez.

ASSISTANT: How can I help you?

USER: Due to some changes in my trip, I want to change my existing reservation. Can you help me?

ASSISTANT: Sure, I can help you with it. There is no reservation with your details.

USER: No issue. Thank you.

ASSISTANT: Thank you for approaching us.