You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: Jonathan Wilson here. I want to change my existing reservation. Can you help me for this one?

ASSISTANT: Sure, please wait for a moment.

USER: Sure, take your time.

ASSISTANT: Sorry, there was no reservation found with your given name.

USER: No issues, thank you for response.

ASSISTANT: Thank you for opting us.