You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: My name is Mark Walker, can you help me to change the flight reservation which I had done recently?

ASSISTANT: Sure, I am glad to help you. Please wait for while. There is no reservation found on your name in our database.

USER: That is ok, thank you for assisting me.

ASSISTANT: Thank you for choosing us.