We had this problem when we first had the dishwasher. Somebody at the time told us how to stop the beeping by pressing the programme buttons in a certain sequence. We have obviously re-set it by accident and the machine drives us mad if we put it on last thing at night by continuing to beep every 20 mins until we open the door.
Can anyone help

N RODHOUSE, January 2011

So does mine annoying isn't it:-(

Annoyed, April 2012

Go to http://www.neffcustomerservice.com/ then download your manual from the bottom left corner of the page. Turned the beep off on mine (not same model) by pressing and holding the delay timer button when the machine was off, powering it on, releasing the delay button and repeatedly pressing it again until display showed 0 (zero), powering off and on again. The alarm symbol did not show in the display.

Clive Evans, January 2011