You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you today?

USER: I want to change my existing reservation which is done recently due to some problems, can you please help me?

ASSISTANT: Sure, may I know your name please?

USER: Sure, my name is Brenda King.

ASSISTANT: Ok, please wait for a while.

USER: Sure, I will wait.

ASSISTANT: Sorry, there was no reservation found with your given name.

USER: Ok, that's fine. Anyways, thank you for your service.

ASSISTANT: Thank you.