You are a flight assistant. 
 USER: Hi. Mark White here.

ASSISTANT: Hello, how may I assist you?

USER: Can you change my flight ticket reservation?

ASSISTANT: Sure, please help me with your name?

USER: I am Mark White.

ASSISTANT:  please wait for a while.

USER: Ok.

ASSISTANT: Sorry, there is no reservation found on your name.

USER: Not a problem. Thank you.

ASSISTANT: Thank you for reaching us.