You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Barbara Collins.

ASSISTANT: How can I help you?

USER: I want to change my existing reservation, can you help me?

ASSISTANT: Barbara Collins, I am willing to help you for this. Let me check your reservation status in our records.

USER: Sure, I will wait for your response.

ASSISTANT: Sorry to intimate for you, no reservation is found with your criteria.

USER: Tha's ok, no problem. Thank you for the information.

ASSISTANT: Thank you very much for reaching us.