You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I render you today?

USER: Please help me in changing my reservation with the name of Brenda Williams.

ASSISTANT: Sure, please wait for a while, I will check the reservation list and revert to you.

USER: Ok.

ASSISTANT: Thank you for your time. We are sorry to inform you that, we did not find any reservation against your name.

USER: No problem. Thank you for your service to me.

ASSISTANT: Thank you for reaching us. Have a good day.