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

ASSISTANT: Hello. How can I aid you today?

USER: I want to change my existing reservation. Can you help me with that?

ASSISTANT: Sure, please wait for a while.

USER: Ok.

ASSISTANT: Sorry Mark Wright, no reservation done on your name.

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

ASSISTANT: Thank you for choosing us, have a nice day.