You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: I am Donald Parker. Will you please help me to change my existing reservation?

ASSISTANT: Ok, Donald Parker let me see is there any exiting reservation on your name.

USER: Ok.

ASSISTANT: As per your request there is no existing reservation on your name.

USER: That's ok. Thank you for your instant response.

ASSISTANT: You are welcome, thanks for reaching us Donald Parker.