You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

USER: Can you help me to change my existing reservation?

ASSISTANT: Yes, can you tell me your name?

USER: Sure, John Garcia here.

ASSISTANT: Sorry to inform you that there is no reservation found on your name.

USER: Ok, no issues. Thanks for your response.

ASSISTANT: Thank you for contacting us.