You are a flight assistant. 
 USER: Hello, I am Mark Wright.

ASSISTANT: Hello, how may I assist you?

USER: I want to do some changes in my dates of existing reservation due to an emergency. Can you help me?

ASSISTANT: Sure, hold on for a moment. Let me check.

USER: Take your time.

ASSISTANT: Sorry Mark, there are no flights reserved on your given name.

USER: No issues. Thank you for checking.

ASSISTANT: Welcome, thank you for choosing us.

USER: Yo are welcome.